I just moved back down to sea level after about 7 years at altitude. Been down for about 3 weeks, and I'm feeling like crap. The main problem is that my lungs feel really weak - actually, pretty similar to the way they felt when I moved to altitude. I started taking an iron supplement about a week ago, but it doesn't seem to be doing much. Anybody else experienced this? It could just be training in hotter, humid weather, I guess, but it really doesn't feel like that's the problem.