Work related

So my boss knows I'm pregnant, I'm only 9 weeks but I told her early due to having horrendous sickness, I have Hg and have been to the doctors several times for different anti sickness medication all of which haven't really worked. I've had a couple days off due to how bad my sickness is (all day everyday) I'm at risk of getting dehydrated as it's hard to keep fluids down. Today I had a meeting with her and she said pregnancy sickness or just general sickness I'm losing money because of your off sick and if I'm off sick again she will file a grievance against me! Can she do this!? If me being off is pregnancy related? So angry and of course I'd rather not be feeling sick and being sick 24/7. Does anyone have any advice? What can I do or what should I do??