What Causes Swollen Calf Muscle?

My left calf muscle is swollen and I have a tender, knotlike spot. The swelling goes down to my sock. I noticed this 6 days ago and have been icing it every night. Still swollen today. I noticed the problem after jumping on trampoline mats at a jumping place. I really don t know for sure what I did. Thought it would be better by now. It does not hurt all that much to walk or run. Should I get in and have this checked out right away?