Most male bettas will have swim bladder issues if you overfeed them. Female bettas , on the other hand , seem to suffer less frequently with buoyancy problems than the males, but you should still have to be very careful feeding them also.  Remember a betta has a very small stomach, so avoid feeding it flakes or freeze dried food that can swell up when mixed with water.  Feed your betta quality pellets and frozen live food such as blood worms.  If you find your betta still have trouble with its swim bladder on a diet of pellets, pre-soak the pellets with water for 5-10 minutes before giving them to your betta.

If your betta currently has trouble swimming, starve it for about 3 days and feed it tiny pieces of peas.  Repeat the process again if his swim bladder doesn't go away.  Once your betta is back to normal, you should starve him 1 day a week and feed him pea the next day. 

Avoid the temptation to overfeed your betta, because it will just eat nonstop all day if you continue to feed it and eventually end up not being able to swim properly.