My Achilles tendon (I think) on the back of my ankle where the top of my tennis shoe sits has a lump on both sides. I blame this on a pair of tennis shoes I wore for a short time that were extra tight at the back top part of the shoe. Now after exercise then sitting for awhile, it is painful and hard to walk. I participate in a team class three days a week that consist of activity on a treadmill. My general practitioner gave me stretches to do, I do these all the time, but still have problems. Any recommendations?