I'm afraid you're gonna have to amputate.
a more detailed explanation of the exact situation and pain felt would be helpful. Were you bringing a curl down rapidly and feel a stretch and pain on trying to bring the curl back up? Could indicate a slight dislocation that allowed a tendon to get caught in between when the joint closed?
When you gently straighten the arm and touch the area that hurts is it in the forearm, bicep or right at the joint and is there any swelling? When pressing with a finger tip and an ability to isolate it to the Biceps Tendon an anti inflammatory such as ibuprofen, ketoprofen are helpful. Not all acute injuries demostrate acute pain to go along with. No harm in treating it as a mild injury but you will want to get it seen by a profesional.
General first aid:
Apply ice immediately to reduce swelling. Wrap the ice in cloth -- avoid using ice directly on the skin. Apply ice for 10 to 15 minutes every 1 hour for the first day. Then, every 3 to 4 hours.
Use ice for the first 3 days. After that, either heat or ice may be helpful.
Rest the pulled muscle for at least a day. If possible, keep the pulled muscle elevated above the level of the heart.
Avoid using a strained muscle while it is still painful. When the pain subsides, start activity slowly and in moderation