4 months pregnant and my are killing me..?

I can understan your pain I too am big ed pre-pregnancy and now bigger, my nipple get red raw when they are about to leak the yellow white liquid. That liquid is colostrum (lactating) that you need for baby. I too had them really sore to touch but if it is really bad mention it to your doctr and in the mean time try wearing the sofest clothes you have and soft bras to relieve some pain