My male boss just said my period pain is “not a real medical reason” to WFH and I can’t stop thinking about it

I’m 30F, work in a small office, mostly guys, mostly 40+. We are allowed to WFH 2 days a week no problem. Yesterday I messaged my manager that I wanted to WFH instead because I woke up with really bad cramps, the kind where you feel it in your back and legs and you’re lowkey nauseous. I have an IUD and sometimes day 1 just hits hard. I said I could do all my tasks from home. He replied “we can’t let people WFH for non medical reasons, please come in.” I said it is medical. He said “I mean like doctor note medical, not period discomfort.”
I still came in and of course spent half the morning in the bathroom trying not to puke. Later he made a comment in front of 2 coworkers like “everyone wants to WFH lately, next it will be because their horoscope said so.” I just smiled because I hate conflict but inside I was so angry. This is a normal function of half the planet and he just decided it’s not valid because it doesn’t happen to him. I keep thinking if a guy said he had stomach flu or migraine he’d say ok stay home. I don’t even want an apology, I just want him to take women’s pain seriously without me having to bring in a doctor to prove my uterus hurts.