I have a abcess on my arm underneath the elbow and its gotten pretty big and its really hard and red jus wanted to get a opinion on what i should do??

See doctor ASAP: Abscess diagnosed by a doctor? If growing, pain increasing, etc, check back with her. How big is "large"? If over an inch or so and you haven't seen a doctor, do it now. You probably need an antibiotic, maybe surgery to drain pus. Something like this could be quite dangerous if not properly cared for. Do it today; if your doc isn't available and nobody on call, go to urgent care or ER.