It sounds like what you have is a ganglion cyst. These are small growths that form usually in the hand or wrist. They are fluid filled sacs that grow out from the sheaths of tissue that surround the muscle tendons in the hand. Fortunately, they are not cancerous or dangerous in any way.
In fact, many times ganglion cysts will just disappear on their own with time. Therefore, unless the cyst is causing you a lot of pain, you should probably just leave it alone for a while. If it gets better, no treatment is necessary. If it grows significantly or begins to hurt, you can discuss the issue with your primary care doctor
Breaking the cyst is a old folk remedy for ganglion cysts. Unfortunately, in addition to being painful, it doesn't work very often - usually the cyst just comes right back. So, I definitely advise against that. Sometimes your doctor may try to aspirate some fluid from the cyst with a needle, which can relieve the pressure for a time.
Large cysts may need surgical removal. This is a simple procedure, however the major problem is that there is no guarantee that the cyst will not come back again after the surgery