Could just be your mind getting the best of you. I have BAD IBS and if I let my mind get the best of me, it gets worse.... especially when it hits me out of nowhere (most especially in the middle of the night). Im sure your cycle isnt making it any better! Try to take a breath, sip something soothing (ice chips and ice water for me, but its different for everyone, what works) and try to find something to focus your attention on. Sometimes getting your mind off things makes it better and gets you out of your own head. I hope you feel better!