Here's one suggestion from PPP's bulletin board"
http://bbs.eatprotein.com/cgi-bin/u...t=003807#000001

Are you taking vitamins with breakfast? Or before? That can irritate your stomach lining.

Or from our own board:
http://forum.lowcarber.org/showthre...pain#post338868

http://forum.lowcarber.org/showthre...ain#post1091000

http://forum.lowcarber.org/showthre...Pain#post165029

http://forum.lowcarber.org/showthre...ain#post1220943

http://forum.lowcarber.org/showthre...ain#post1095714

Not everything comes from LC, so if it continues, you should probably see your own doctor. hope this helps.