What now? what can i do for my betta?

i have a betta fish that lives in a 2.5 gallon tank with a heater, filter and plant with an ornament he can hide in...he was always on the floor and would never be swimming around, i decided to check his water and found that ammonia and ph was bad so i changed water partially every day, and i tested the water today and ph is perfect and ammonia is nearly yellow..and he still looks the same...is this swim bladder? he would be hangin around the filter, and lie on his side someetimes...really strange, i dont know what to do