Just find out I'm pregnant while breastfeeding pls help

I'm 8weeks . First doctor appointment is next month the nurses have been calling for me to start taking prenatal vitamins. since I was breastfeeding I'm kind of scared for my 10 months old daughter I think the vitamins will be just too much for her. Immediately I stopped breastfeeding because of the stress, nauseous, stomach upset, back pain and lots more. My breast is so hard like stone for four days now. Can't sleep, when she touch my breast I shout, can't carry her for too long . Seriously need help with the pain or should I pump?