Sounds like Swollen lymph nodes. My dad had them in the same spot as you. They are painful.
http://www.webmd.com/hw-popup/common-sites-of-swollen-lymph-nodes
http://www.webmd.com/a-to-z-guides/swollen-lymph-nodes-topic-overview
The knots under your arm pits are most likely swollen lymph nodes. Are you sick? Do you have any other symptoms? Any fever? If you are in a lot of pain you could go to an urgent care clinic if there is one in your area, and the ER will always take you as well if it is really bad and can't wait. Are the knots really tender to the touch, and are they hard or squishy?
Have you tried taken any Motrin or Ibuprofen? That might help with inflammation and pain and it is over the counter. If you have already taken OTC's and are still in a lot of pain you should call your doctor and see if they can work you in, and if not they can advise you what to do.