That's funny. I've had exactly those symptoms with several different treatments. The first ever time was with a gluten and casein free diet. That one was horrendous! Up in the middle of the night, every night for a week, with either howling cramps or, er, the other thing, or both. This is supposed to be a good sign as it means you are getting opiate compounds out of your system, so the diet will work as soon as you've finished that stage - they call it the withdrawal phase. The funny thing was, the symptoms did go away after a while, but it never did all that much for the OCD! I kept up the diet for about six months, then gave up.
Then I had exactly the same thing while taking SAMe. Not immediately, but after I'd been taking it for a few days. I stopped taking that pretty sharpish. It did seem to help slightly, but honestly!
And I've had it just recently, too, after a few days of taking St. John's Wort regularly. It seems to have gone now, touch wood. I had a brief bout of intrusive thoughts at the same time, but don't know if the two things are connected.
Does this suggest anything to anyone? It's got me baffled.
Wombat140