Just phoned in sick, period so painfull

I've just come on this morning and am having the worst period ever, I actually feel like I'm going to give birth, so painfull, I only work for a few hours s day, but have just phoned in sick, can't stand the disbelief in people's voices, if you don't suffer with bad periods, how can you dare to be opinionated about it, I'll probably struggle to go to the kitchen and get a sandwich today, I certainly can't walk around a playground for an hour. Arrrrggggggg.