I went for 5 days to my friends house on the island, and I had got my brother to take care of my goldfish and betta. I got back last night, ad all my goldfish are doing great, and I swear my little telescope has even grown. I was releaved that eveything went over smoothy untill I walked over to my betta's tank. He lay at the bottom of the tank, and didn't move 'till I turned on the tank light. I noticed his stomache looked bloated...could he be constapated? Also, he shows a loss of colouration. I noticed that at the hole at the top of the tank where you drop the food in had a bunch of rotting food there that hadn't made it into the tank..I don't think my brother niticed it didn't go in. I don't think that affected water quality because it wasn't near it, but there is a lot of uneaten food at the bottom of the tank, which I have to go clean out after I type this. I fed him last night and this morning, and he ate fine. What could be wrong with him? I will go take pictures now, and they should be up in the next half an hour.
Thank you for any help!! Davey and I will apperciate it.

You'll be lucky if it is just constipation, but saying that, constipation can kill. Dont feed him for 3 days and then see how he looks.
If hes unlucky then it could be a bacterial infection.
Keep his water warm and clean and hopefully he will be ok.

Thank you...I'll see how it goes. Is there anything special I should feed him after those three days?

Here is a picture...terrible quality, but its sadly the best I could get.
You can kind of see a little bit of a bump on his chest...hard to see. And maybe its just my imagination, but I think it's gone down since last night.

Bump..