My right ear is muffled, like im under water. But my left ear is fine. And it wont 'pop'. Is this serious or could it just be wax build up?

Probably wax. Go see an ENT doctor. If its wax it can be easily removed, if not you are in the right place for an appropriate work up and evaluation.
Could be. Could be wax. You should see your doctor to have a look. Wax can be removed. Is your nose stuffy? Do your have allergies? Antihistamines, Flonase and nasal saline flushing can help. Osteopathic manipulative treatment of your head could also improve eustachian tube dysfunction that could be another cause.