i had good form, abs were tight, i was warm, etc. i've done gm's for years and never had a problem. on my first set last tuesday, i loaded up 155lbs and went at it.. around the six rep i felt a weird twinge in my lower back, just to the left of the spine. i refocused, kept my core tight, and finished off 10. it was obvious though that there was something wrong so i called it a night. the pain was pretty bad the next couple of days. i've been taking 900mg of naproxen, icing 3-5 times a day, and doing various stretches. i'm fine walking around and what not, but bending forward still bothers me. any ideas what i've screwed up? cliffs: did gms a week ago, felt twinge in lower back. been icing, resting, etc. feeling better, but still can't bend forward without pain.