What to do about my bicep injury?

I started again with dumbbell exercises yesterday, foolishly without a warmup, and even though after the concentration curls the biceps just felt stiff, as hours ped, my left lower bicep, adjoining to the forearm, really started burning. At this point, I can't hold out my arm straight without severe discomfort. Only keeping it curled close to my chest, as when typing, keeps the searing minimal. How long does this type of thing take to heal? And is this an indication I used too much weight?