it feels like a cross between trapped wind and menstrual cramps and starts thirty or so minutes after I take the tablet. I've been persevering for three days and I feel like giving up as I can't sleep though the pain, it's worse than the pain I'm taking the naproxen to combat! ( inflamed shoulder tendons) I took omeprazole this morning to try to avoid the pains but they came anyway. Any advice? Shall I persevere or give up and go back to ibuprofen? I feel like a sausage about to burst!