I got the TetraBetta floating mini pellets and it is not heated. My roommate and I keep the temp between 75-80 degrees so I wasn't sure if I needed one. I'm also waiting for some money to come in so I can get some other things for him, like maybe a heater, if needed, and possibly a bigger tank, as I have him in a 1.5 gal right now cus I read bettas should be in at least a gallon, but most people here seem to advise bigger, though as I am in a dorm I can't get too huge of one..
I filled the tank with purified water but I also ended up putting in water conditioner as well, just to make sure.
Ok you are doing good, it's probably just that he's a bit stressed from being moved into his new tank. I haven't tried that fish food, but members on this forum recommend New Life Spectrum or Omega One pellets. I don't think you need a heater for now. My room is the same way, so I keep my tank unheated and my betta is fine. A tank of minimum 2.5 gallons is recommended for bettas, but until you can get a bigger tank he will be fine. Just make sure to keep up with water changes.
His head is black and the rest of him is dark blue, he does look more dark grey in the picture but that's shortly after I got him so his color wasn't so vibrant. I got the rock hide outs at Walmart, he loves them haha