I'm not sure where to ask this. I have been on flexiril for 1 week now. 1 or 2 every 8 hours. I have not been taking it regularly until Thursday, hoping it would help with the pain. I have not noticed any pain relief form them. Saturday night I was woke up by terrible cramp like pains lower let side abdomen & back. This hasn't gotten better. It stings & almost feels acidy like ibuprofen does. Could it be the flexiril? I'm not going to take it today & see what happens.