I don't have CF but I too have horrible periods every few months, like they gradually get worse and then "explode". I don't have endometreosis, cysts.... either. I use Naproxen Sodium (by RX) and it works wonders if I utilize it at the first inkling that I might be starting to cramp (my period is also somewhat irregular, 35 -40 days instead of every 28. This year has been the worst, onc time on a saturday I was in bead with a heating pad, rollig around from the pain, moaning, and then, I had to throw up. I hadn't taken meds in a few hours, but hadn't caught it soon enough with the naproxen. I was throwing up from the pain, my stomach was in such torment. And then a few months ago-at work of all places, it started immediately with bad cramping. Tried the naproxen (hindsight telsl me I should have used it the night before when I thought I was starting to cramp but couldn't be sure). I had the urge to go to the bathroom (of course) and felt faint on the toilet, started cold sweating, shaking.... finished up and was walking back down the hall when I fainted-FAINTED. Luckly 3 guys were walking back and saw that I was leaning against/trying to grab the flat wall and they caught me. I spent the afternoon upstairs in the ER. The doctors were asking me, "are you normally this white". I was so ticked off by the question at the time, I was like, I don't know. And then when the next nurse, and next doctor, and next nurse.... came in and asked me the same question, I was like, "how about a mirrior or something so I can answer that question". They finally got an answer when Mark came into the ER, NO she is not normall this white, NO she has never fainted before and we've been together 6 years....
It was a period I will never forget (sorry for the life story)