Pirformis, tendonitis, bursitis, or something else?

Since last June after every race I do I get glute soreness and around soreness around outer waste line.  I doesn't hurt to walk, bike, or swim ( and I don't even feel it).  It doesn't hurt to run but it makes it difficults because its uncomfortable.  I noticed it the most the last two days getting out of bed but it would go away with a minute or two after moving around.  It seems to get better with rest and goes away immedetly when I stop running.  The other race I did in the Summer it would go away with a few days of rest and reduced training but I could ramp up really fast with no problem.  I was running 50+ miles the last 8 weeks.  I did a 10miler 3/2/13 and was fine until I woke up Wednesday (3/6/13) with this glute soreness and hip soreness. (its more tightness/uncomfortable than sore). 

Any thoughts on what this might be?