I don't know why i am breaking out in hives? help?

Common: The cause for chronic hives (lasting more than 6-8 weeks) is often unknown. However you may try taking antihistamine up to 4 x the regular dose to see if it helps. If not consult an allergist.

Many things possible: Assuming this is new for your, the most common cause is infection (often very minor in nature) resulting in activation of innate immune pathways in skin that trigger mast cells. Usually, hives resolve and we never know the cause. For other causes: http://emedicine.medscape.com/article/137362-overview#aw2aab6b2b3aa. A virtual consult to discuss triggers can help.