I am sorry to hear about your own problems and now these worries about T. I just came online; I am sorry you did not get help from an expert until now. My name is Rebecca. I am a veterinarian and will do my best to help.
It sounds like there could be a problem in the nerve function to his back end, or his spinal cord. It could be a slipped disc, a condition called FCE (fibrocartilaganeous embolism) where a piece of cartilage gets lodged in the spinal cord, a stroke (blood clot in his spinal cord). I could not tell you for sure what this is, without being able to examine him.
An FCE is actually good news; these dogs get better with time. If he has a slipped disc, he may do better with things like anti inflammatory medication (aspirin is OK, often we use carprofen or meloxicam, etc.), pain medication (tramadol, gabapentin), and muscle relaxants (methocarbamol; do NOT give a dog Flexeril,a muscle relaxant for people). However, some dogs with slipped discs do not recover, or may need surgery.
Panting can be a sign of pain. Has the aspirin helped at all? I am sorry to say that it sounds like he needs to be seen and treated by a veterinarian. If my own dog had these symptoms, I would not be trying to treat at home.
Let me know if you still need help or have gotten help, and if you have any more questions I can answer.