I was hoping for a response to my request for more information but I don't what you going too long without an answer. He needs some chew toys that are just his. Kongs filled with yogurt or peanut butter that does not contain xylitol then frozen before given to the dog make excellent choices. He needs at least 6 plus toys as you can only have half down at one time and need to rotate them to keep the dog's interest. In addition, run free cords through pvc pipe to prevent him chewing on them. Electric cords can even cause death if he chews through one. I understand you can not do that with your oxygen tub but you can put bitter apple spray or hot sauce on the outside to discourage his chewing on the oxygen tubing that has to remain able to be moved around.
He needs to have obedience training as well. This will help stop him from biting and lunching. That is his way of reprimanding you for doing things he doesn't want you to do such as making him move or you moving when he doesn't want you to. Only the boss is allowed to reprimand so you need the obedience training to show him you are the boss. The following site is helpful in helping owners train their dog. Be sure and click on the link to the page on obedience at the bottom. and links on subsequent pages leading to detailed instructions.
Training works best if you train at least 30 minutes a day (two 15 minute sessions). I would start making your dog work via the Nothing in life is free program (NILF). It is outlined below.
Additionally, his licking and chewing on his paws may indicate an allergy condition or a thyroid condition. A thyroid condition might also explain his sudden aggression as we do see this with dogs having thyroid imbalances. So you will want to have a thyroid panel done at a minimum. Your vet can also check to make sure there is no yeast dermatitis present on the paws already from the licking and chewing. If there is a yeast dermatitis which frequently causes a musty odor, you can use miconazole cream on the paws and use an e-collar to stop his chewing until the dermatitis is cleared up. Benadryl can be given to your dog, the dose is up to 2mg per pound every 8 hours for itching due to allergies.
You can read about allergies here: http://www.vcahospitals.com/main/pet-health-information/article/animal-health/allergy-general-in-dogs/428
If you are unable to exercise him, see if there is a teenager in the neighborhood willing to take him for walks. Terriers are high energy and can become bored easily. If you have a yard, you might invest in a ball thrower and let the dog learn to put the balls in which lets him play on his own for hours if he wants. See one here:
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Since there have been recalls on certain foods, please check the following site to be sure the food your animals eat is not affected. If it is affected, contact your vet as soon as possible. Have your dog seen if they have any symptoms.