[Noah930]

Like others have already written, sounds like a ganglion cyst. They typically happen in one of four places on the hand/wrist, and that's one of them (roughly located on the palm side of the knuckle?). They usually arise from either the joint/knuckle, or the tendon sheath. They're benign (non-cancerous). Think of the cyst as a little bubbling out of the synovial fluid that bathes the joint/tendon for lubrication--comes out kinda like caro syrup. Haven't tasted it, yet. You can either to aspirate it, though it may come back. If it does, and it still bothers you, a surgical procedure can be done to cut it out. Recurrence is rare after that. There are other things it may be--giant cell tumor of the tendon sheath, inclusion cyst, Schwannoma--but they're almost all benign. Seattle is loaded with excellent hand surgeons, so let me know if you need any names.