can prometruim cause sore nipples after 9days, or could it be preg?

Yes Trisha, it can cause the symptoms. I read u took a blood test and it was negative, so at this point, its the med thats giving these symptoms :( Unfortunately it does take a few tries..If you strongly suspect u could be pregnant then theres no harm waiting for another week and testing again and then quit.

U wont get ur period unless u quit prometrium.

Another thing is ask ur Dr if he did a qualitative blood test or a Quantitative (Beta). Quantitative is more accurate, it gives u the amount of HCG present. A qualitative will only tell u preggo or not based on a standard set by that lab.