My left breast is tender, warm and I noticed a small discharge that looks like blood from the nipple yesterday and today.

See your doctor asap. To have this evaluated as a bloody discharge is not normal.
Swollen lymph nodes? Bloody discharge, tenderness and warmth may mean infection if lymph nodes in armpit swollen. Best thing to do is go see a doctor for possible antibiotics. Imaging studies may also be needed pending his/her physical exam of your condition.