Greetings, I am Dr. Pat. I have worked with birds for many years. I will do my best to help you. I am sorry no other expert has taken your question. We all come online at different times, I have just logged in and saw that you have not been answered. I hope I can still be of assistance. Just as in the real world, there are fewer bird-experienced vets online than non-bird vets. I wish it was a different story.
In cockatiels, diet is the number one cause of feather problems. Infection (bacterial, parasitic, fungal, viral) and toxicity run close second and third. I realize there are not many vets to help, but you may need to hook up with a regular vet, at least take in some poop samples and feather samples (if not the bird) and have them consult or do telemedicine with a specialist. It is very important to rule things out and get started on a good treatment plan, as he is too tiny to chances and guess (and guess wrong).
Chewing paper etc is often associated with reproductive behavior, and an overload of hormones can be caused from increased photoperiod (they should get no less than 12-14 hours dark quiet uninterrupted sleep at night), high-fat diet (seeds) and seasonal changes ( a warm house is just perfect for reproduction).
Do not feed human baby foods of any kind. The vitamins and mineral supplements in them are toxic levels for birds and may in fact make the feather condition worse. He should not get meat or egg at all. There is much misinformation about this but botXXXXX XXXXXne cockatiels cannot assimilate animal protein properly and it can kill them or exacerbate other conditions. If you have a pet store nearby, a good quality baby-bird hand feeding formula is a much better choice (Exact can be found almost everywhere). High-quality pellets can be ordered online (see the feeding guidelines below).
Cockatiels are commonly infected by spiral bacteria, protozoan parasites of the GI, Macrorrhabdus, many staph and strep, Borna Virus, and occasionally with Beak and Feather Virus. Simple mouth swabs, poop samples and a few feather samples can be sent to avian-specialty labs by a regular vet to start ruling out the possibilities.
Feather issues can be caused by a multitude of things, including bacterial skin infection, viruses, fungal infections, allergies, metal poisoning, hormonal flux, psychological or combination of these factors. The difficulty is diagnosing the problems and assigning an intelligent treatment plan. Your vet will want to run a number of tests so that appropriate medications can be prescribed.
Inflammatory skin/follicle disease is common. The causes can include local infection, metabolic problems, or even intestinal parasites. It can also be a prime area for even more serious problems like skin cancer. An avian-experienced vet should take a look at the poor bird, and run some tests. If he were my patient, I would start with complete fecal analysis and direct smear, bacterial culture and sensitivity of the feces, skin, feather pulp, and choana. Depending on the case I might do a fungal culture. Routine blood work is necessary to rule out other issues. Generally I start them out on injectable antibiotics and an anti-inflammatory such as ibuprofen.
Without a diagnosis, I cannot recommend any particular course of treatment, except good nursing care at home.
If you feel comfortable with it, examine the bird thoroughly, using gentle restraint via washcloth or hand towel: do not restrict the chest or hold around the body. Check the eyes, nostrils, mouth and beak if possible, having a good look in there for mucus, redness, masses or anything else unusual. Palpate the tummy for pain, fluid, lumps or anything else (eggs, if female or unknown). Check all the joints for swelling, pain, and mobility. The feathers should be parted to view the skin, muscles and skeleton below; this can be done using a q-tip with isopropyl alcohol or KY gel. Look for bruising, lacerations, injured feathers.
Pet/feed store medications and home remedies are harmful, ineffective, immuno-suppressive, and make them much worse and may interfere with the veterinarian's diagnosis and treatment. Do not use them. Homeopathy and natureopathic techniques do not work in avians and can actually be very dangerous.
Here are a few suggestions that I give everyone: important!The following guidelines help with basic issues such as nutrition, obesity, good immune status. Surprising how the following can make a bird healthy, and how infrequently birds are ill if they are on the following regimen. No amount of medicine is going to work if the birds' basic needs are not met.
Basic Care Birds should be on a high-quality, preferably prescription, pelleted diet: I prefer High-potency Harrison's
http://www.harrisonsbirdfoods.http://www.harrisonsbirdfoods.com/products/harrisons.html TOP
http://totallyorganics.com/t-pellets In addition, they should be offered dark leafy greens, cooked sweet potatoes, yams, squash, pumpkin; entire (tops and bottoms) fresh carrots and so forth. No seeds (and that means a mix, or millet, or sprays, etc. etc.) and only healthy, low-fat high fiber people food. A dietary change should be closely monitored and supervised by your avian vet.
Daily Maintenance
Birds should get 12-14 hours dark, quiet, uninterrupted sleep at night. Any less and they can suffer from sleep deprivation and associated illnesses. They should be covered or their cage placed in a dark room that is not used after they go to bed.
The cage material should be cleaned everyday, and twice a day if the bird is really messy. Paper towels, newspaper, bath towels are ok. Never use corn cob, sawdust, wood chips, or walnut shell.
Food and water dishes should be cleaned and changed daily. Keep one set cleaned while the other is in use.
Fresh, perishable food should be placed in separate food bowls. Remove fresh food from the cage after a couple of hours to avoid spoilage.
Change cage papers daily, and clean the grate and tray weekly.
Clean food debris or droppings from toys and perches as needed (which can be as often as once a day).
Grit is not necessary for birds, and will cause digestive problems and death. The best sources of minerals (and vitamins) are leafy greens. Never give grit, gravel sandpaper or cement perches. A bird will eat those to excess when it is not feeling well or if there is a nutritional deficiency. They do not need it at all (an old myth from the poultry days, even poultry do not need it). It can cause an impaction and lead to serious or fatal consequences.