Mastitis or engorgement

I'm a FTM and 5 days post partum. I have only breastfed a few times.  I mostly usually only do the  right breast which was a mistake. But that's the nipple that the baby takes. 
Well now my left breast is rock hard, sore,hot to the touch, nipple is burning and I can't move normally or even walk without it hurting so badly. I can't pump because it is agonizing.