Unusual cramping? TMI

So I've never had this happen before, but it has happened twice in the past 4 days.

So twice now when I have started to play with myself, when I'd get close to orgasm I'd get really bad cramps, worse than I would get during pms. According to glow I was ovulating for one of those incidents, and just having finished for the last one, but my periods have been very irregular so who knows.

Any ideas what this may be?