Inventilicious

I'm a guy still reading advice sites on how to not prematurely ejaculate during masturbation yet feel pleasure through most of the session, as when living with my parents, I trained myself to do it quickly and quietly. Now to untrain.

Cramps? Yeah, the latest thing I've discovered is that if my feet are stretched out as I approach orgasm, my toes cramp. Ow. If I carefully keep my feet flat on the ground, my stomach cramps like hell instead of an intensely pleasurable sensation during orgasm. What's up with that?

I, having no medical experience, don't think it's a medical issue. I think it's just I'm doing something wrong. I will of course continue to experiment, but wanted to ask around.