I am sorry to hear you are worried about Baby Girl. My name is***** am a veterinarian and will do my best to help.
I see she is overweight. Losing weight will help her arthritis more than any medication or supplement; are you trying to help her lose weight?
I would give her enough fish oil for her to get at least 500 mg of Omega 3s (DHA and EPA) daily. Vitamin E would be fine, about 100 to 200 unit a day.
The yellow liquid you are asking about may be known as Panalog, or Animax, or Enterderm. They are all the same, a combination of steroids and antibitoics. You do need a prescription from a veterinarian to get it.
The chondrotin, glucosamine, manganese, etc in the osteo biflex should all be safe in a dog her size, but I would give about 1/2 the dose recommended for adults. 5 - Loxin has not been tested in dogs, but I could not find anything saying it is a problem or toxic to dogs. You might consider a product made just for dogs, such as Dasaquin as a joint supplement.
If she is in pain, I might try her on prescription pain medication like tramadol and nonsteroidal anti inflammatory meds made just for dogs like Rimadyl or Metacam or Previcox. You can give these with steroids, so you would have to wait until the steroid injection wears off.
Let me know what other questions you have.