Thank you all for your replies.This is why I love communities such as these, people are always willing to help.Did a little research and found out there is a pet supply store that sells high end quality foods a few blocks from my house.I will go there this weekend.
I will try something with no grains and make sure he gets more exercise, whether it be walking or swimming.I love the idea of swimming since it's low impact, but I dont know where to do it. My bathtub is not deep enough and all the pools around have a strict no pet policy. I will look into some other options.
Thank you all again, I will post progress and updates.