Sounds like it could be IT-Band friction; the site of pain seems to tie in with the Band's insertion. As you said, it often arises from overuse, combined with tightness (or lack of mobility) around the hips or improper muscle firing patterns. Rest, ice and NSAIDS, as usual for injury protocol, and try foam rolling down the lateral aspect of your thigh, up to the TFL (below the bony prominence of your hip) and around the glutes (a tennis ball works great for this.) Stretch them all out and work on strengthening the glutes with isolation movements (clamshells, etc.) as well as your VMO (terminal knee extensions.) Even if you already have adequate strength around the necessary parts of your hips, this will help to maintain and improve upon that while you recover from the overuse ailment.