Fluffy the biggest sweetheart!!! Help

Hi Everyone
I am dragons and balls better half:-) My name is Rea

I have an iguana that i have had for 8 years.... I have had one before Fluffy and we think he died of some kind of sickness (he died at the age of about 10 years)
Fluffy has been doing great but he has been acting strange..
He usually is VERY tame but lately he trys to bite, doesn't want out of his cage very much, and it seems his mouth is a little swollen. He doesn't have mouth rot... I have already medicated him for that and also his toe nails are starting to fall off. He has had calcium supplements threw out his life but from what I see thats out there today, I don't think the ones I used to give him are doing much good. If u have any suggestions.. please let me know... Is he on his way out???

thanks
Dragons and balls