I am not a DR and I am not giving medical advice but I have had this problem numerous times myself without the pain. Im not entirely sure of the mechanics and no DR that I have been to can tell me what is going on. But for me it takes as long as a week for it to go away. Its like a pressure build up in my inner ear, but it feels like there is water in there. I have found that if it happens and I make another dive and I use an assent line and ascend very very slowly it will relieve the problem. It happens to me just by moving my head in the wrong direction while diving but there is never any pain. Any more I can feel it coming and I can stop it by moving my head. But in general you want to avoid dive profiles that involve a lot of up and down and dont do goofy things like somersaults.
Water Monkey - you need to go and see a hyperbaric physician and get your skull x-rayed or MRId - this should not be happening. Up and down all the time is never good but a goofy somersault is great fun and should not cause problems. It is likely you have a malformed Eustachian tube or some other problem with your middle ear. The Eustachian tube changes shape as a person progresses from infant to child and in some cases it doesn't happen. I dived with a lady not long ago who had very similar problems. The "water in your ear" sensation is a squeeze, with the aforementioned blood and spinal fluid getting stuck in there. Assuming your equalisation technique is correct, you have a physiological problem which needs to be addressed.
Cheers
C.