I will try to explain this in the best detail that I can. I have been walking and running barefoot for several months now (still mostly just walking). I have had sore calves from time to time, but now I have this annoying pain on the outer side of my left leg that I can't seem to shake, sort of half-way in between the knee and ankle. It's been continuous for 3-4 weeks now. Sometimes it's barely noticeable, but other times it seems like I can barely walk. Most of the time, if it's just a normal day around the house or office, I can walk normally with no pain. I really only experience the pain if there's any kind of pressure on the area of my left leg. An example is crossing my left leg up over my right knee, or if I'm on the bed or couch and my left leg hangs off the side. That's when I feel pain, and it's almost unbearable when the pressure is released (leg lifted up off of knee or couch, etc). Looking at this image, I believe it may be somewhere in the Plexor Digitorum Longus, along the left side of the lower leg: If I try to run or even walk briskly as part of a workout, the pain will start to occur mainly during the part of the stride where my foot comes up off the ground behind me. I do not feel the pain when my foot comes down onto the ground or when weight is on it. After W1D3 of my E25K program on Thursday, this pain was bothering me. I took some Aleve on Friday and it was feeling better, but then I had to sprint across a busy intersection twice Friday evening while out shopping (wearing VFF's), and after that it felt like I could barely walk. At this point I feel like I should probably see a doctor, but not sure what type of doctor. I may just start with my regular Doc and go for my annual exam, which has no insurance co-pay, and then mention the problem while there. I'm really hoping it's not some kind of stress fracture or micro-fracture in any of the bones. However sometimes the pain does feel like it's coming from the bone, so I don't know. I'm guessing I need to take off from walking or running until I get this figured out.