What can be another reason a female nipples are sore for more then a week? could it be ovulation? can back pains be part of ovulation also?

Nipples can also be sore from other hormonal changes, friction,sexual activity. An associated rash suggests allergic reaction. I wouldn't attribute back pain to ovulation.unless painful urination occurs. Your gynecologist can advise you further.

When was your last period? Have you check HCG level? Would follow up with gyn for testing and possible ultrasound as well