Cat Stomach Inflammation

I wasn't really wanting to start something like this here, but since I'm always deeply worried about my cat I might as well. He's always been an injury prone cat. This time, he has some inflammation in his stomach. I'm not sure what it is, so I'm definitely going to the vet soon. Actually... now that I look at the picture, the bump is in a weird place. I'm just gonna put this here since I needed to get it out of my system, and I want to hear if any of you guys know what it is.

Unfortunately  there really isn't any way for us to diagnose what might be wrong, and to speculate would just not be right, for YOU or your little guy. 

Does he appear to be an any pain when you touch the "bump"?  Is he eating and pottying normally?   Does the bump seem to be changing?  You said it seems to be in a weird place...did it move?  All things considered, to ease your mind, you should probably get him in to see a Vet sooner than later unless it's disappeared by now.

The bump disappeared, but I'm still going to take him to the vet. 

Is he acting strange?  I wonder if it could have been caused by just a positional thing? 

I went to the vet a while ago, and they told me to change his diet. I changed it, but he still get's bloated.

Gosh, it's been over a year since you posted on this thread, so guess things are too bad. So when you say he gets bloated, do you think it's just gas? If so, then perhaps he needs yet a different food still. That would be my guess. Some cats have very sensitive tummies and can even be sensitive to chicken, which is in a lot of cat food. What food did you switch him to?