Problem with my 3 year chihuahua

Question
In the last couple of days, my 3yr old Chihuahua yelps like something is hurting him. He is sleeping more, not as energetic and I notice he is sleeping on the arm of the chair and not flat. He also is having trouble jumping on the couch and bed. Some background info:  he is about 5-6 lbs overweight and he is on seizure medicine. He just had his recheck a month or two ago and the doctor says he was healthy except for his weight. My dogs do eat table food, but I only feed them once a day, since the doctor told us to have him lose some weight. I cut out all snacks and in between feedings. I do not know if he is doing this for attention, since we do spoil him or if something is physically wrong. When I was petting him, I touched him everywhere to see if something was specifically hurting him, but nothing did. So basically the yelping is what is bothering me. If you have ideas, I would greatly appreciate it!

Answer
My first suggestion would be to have the vet check him over again. Is he yelping when he jumps of furniture? My first thought might be arthritis but he is young. It could also be the extra weight he is carrying. Also cut out the table food, this is so bad for these little dogs, their pancreas cannot take it. I know it is hard because they are so cute, but an overweight dog is super dangerous and feeding them people food is not good at all. I'm sure you know this but I must stress the importance of stopping that.
With that being said monitor when he yelps, you say he is having trouble jumping, it might be again due to the excess weight. Chi's are tiny to begin with so extra weight puts undue stress on their joints. Has your vet checked his knees? They are prone to bad knees and perhaps this excess weight is adding pressure to his knees therefore making it difficult for him to jump.
I can't provide anything other than that. Please see the vet to check out his knees and please feed him only a high quality food meant for weight loss, no people food! He will thank you later :)