Lower Leg Injury help

[MarkS]

I used to run cross country as a sophomore in high school (4 years ago.) Half way through the season I started noticing dull pains on the outside of my lower leg that intensified the further I ran. I noticed it was especially worse with more intense impact (downhill running or uneven/hard surfaces.) My coach at the time had me run indoors where I was running on flat ground and the pain was noticeably less at first, but after a week or so of running indoors the pain got worse. Aside from pain, the more I ran, I noticed a firm bump formed on the outside of my lower leg (doesn't hurt when I press into it though.) The injury got worse and worse until I eventually couldn't make it to a single mile before I had to stop due to my legs not being able to bear the impact any longer.

Since then I had stopped running and any other activities that involved high impact on my legs. I never really though it was serious as the pain never came back until the same pain and bump on my leg came back when just walking up a steep grade a year ago, and that was only a very short distance, less than a quarter mile. After a few weeks of walking up that same uphill climb, the pain grew worse and worse so I tried changing shoes. That seemed to take care of the problem as I've had no problem with the injury until recently.

I've recently started running again to get back in shape and now the same injury is coming back again. On my first few runs I was able to do 30-60 minute runs without pain but now I'm getting the same intense pain I used to get in high school after only about half a mile... and now I'm thinking I should probably see a doctor about it.

My high school coach, trainer and team mates all said rest and more running would help, but obviously it hasn't if after 4 years I still have the same problem.

I drew the location of the pain/bump in the picture below:
http://img.photobucket.com/albums/v416/radd2/leg.jpg

It's the same on both legs in the same spot, though the left leg is more severe.

Any help as to what it could be or how it can be treated would be appreciated. Thanks in advance!