Betta Fish: Betta floating can’t swim down

I've had this betta about two days, I tried to make sure I was thorough with everything. His tank is about 80° f and has been at a consistent temperature. I don't know the ph levels cause I don't have a test kit and my local store was out so I'd have to order it. His water is filtered and he has a heater. Yesterday I fed him some sera bettagran color food, it didn't seem like he ate much. Today I fed him some bug bites they're small flakes, I gave him a few little flakes about 3 times today, he didn't really eat too much of those either. I just checked on him and he was just floating at the top of the water, he can still swim around but he can't swim down and he looks really bloated. He seemed fine an hour ago. Any advice would be greatly appreciated.