Built up fluid in my eardrums for three years?

You need to relax. If you hear cracking every time you swallow that is the air pressure equalizing in your eustasion tube. That means they are not blocked. The next time you go to the doctor request a referral to an ENT or otolaryngologist. They can check you out and discuss whether doing the Valsalva maneuver will help you or if tubes in your ears is the right course of action. A little ringing in the ears is normal, so don't sweat it.