Can my boss force me to take unpaid leave over a pre-migraine?

I get warning headaches before migraines. If I avoid light & cold I can often dodge the actual migraine. One day I requested to wear my sunglasses at my desk to prevent a migraine, and my boss sent me home, unpaid, instead. (The company is small so I have no PTO or sick days, nor is there HR.) He admitted he did not understand migraines, but then refused to let me explain because he "didn't want to upset me" while I was "sick." (because being forced to log less hours than the cost of the commute isn't upsetting, apparently.) I find this both absurd and discriminatory, and it has prevented me from requesting reasonable accommodations for other things (anxiety) because I don't want to be penalized by his "concern."