I am a healthy 37 year old female... At the beginning of this week I started an exercise group that meets every morning for an hour each day (during the week)... I was doing very well, actually yesterday (Thursday) I did more than I had before, and although I do push myself, I do not push myself to the extreme... I don't believe in putting myself in more pain that necessary... Anyway, I woke up this morning (Friday) and had one heck of a pain in my left side (it feels like someone is stabbing me), next to my left hip (a little below waist level roughly)... I don't have any other problems... This is not an appendicidis or anything like that, FYI... I thought maybe it was a pulled muscle, so I went to class, and although I could do some things like run, other things (like leg lifts I could not do without extreme pain, so I didn't)... It hasn't gotten better even with stretches and such... One of the girls in my class said it was a muscle (and I thought I could remember which one, but I can't now) that women have that gets tight because of bad posture and lack of use... And that now since I am exercising a lot its getting tight... Sorry I wish I could remember more of what she said... Does anyone have a clue what I am talking about and does anyone have any suggestions on what I should be doing to allievate this pain? Not to mention I don't want to make this worse... Any input, questions, comments, etc. are appreciated! Thanks in advance!