Why am I having only "period clots" ?

I've always had heavy menstrual bleeding with no clots, but since my last 2 periods I'm only having a lot of large period clots and very little bleeding. During this I feel like fainting and feel unwell. What could be the reasons? (Also having a lot of hairfall)
P.s. I've been taking acne medications since 3 months. Could this be a reason too?
Don't tell me to see a doctor as I'll be going for an ultrasound next month.