What does my betta have and what can I do to help him ?

Okay. I came home one day to see my littel brothers betta with large puffy eyebulls going out on each side and one weighs more than the other so he is allways on a slant, but know it has gotten worse he can hardly move and when he tries to move he falls over and most of the time he has hes just lieing up strat not moving. What should I do ? I don`t want him to die hes the cutest pink crowtail betta ever !