Pain was deep, ye. Can't answer the question about physical activity because it rendered me unable to do any! But, yes, exerting any kind of physical effort seemed to make it worse.

I would lie on the cold bathroom floor every month with a heating pad / hot water bottle on my stomach, but it gave little relief through the simultaneous hot flashes and cold sweats.

Two things that actually helped somewhat if I could catch it hours before it started were: eating bananas (I suspect potassium helped with cramping), and, weirdly.. drinking pickle juice. Idk what that was about, but it worked.

But have "your friend" get checked for endometriosis and PCOS!!! That shit can actually escape your uterus and scar up / destroy your other organs!!! No joke!!!!