I've been having this on and off pain in my left Achilles tendon. It gets pretty bad at times and it often hurts when I don't move around for long periods of time because I guess it gets stiff. If I don't run for a day or two I'm usually fine, but whenever I run it either hurts minimally to a lot while I'm running, and always hurts at least a little bit thereafter. As I said, it's behind my ankle on the left, where my Achilles tendon is, and feels like a strained feeling. It's swollen and I usually ice it which I think helps, but the swelling is still there. This has been going on for a couple weeks now, but I can't pinpoint an exact time that it happened. It wasn't an injury that I sustained at a certain point. Any idea what it is? What can I do to fix it (I really don't want to stop working out/running...but if I really have to I guess I will)?