I am 2 mos late from period, i have really sore right breast near armpit, cramps, nausea, neg pregnant tests. if i'm not pregnant what could this be?

Hormone imbalance: It sounds as if you likely have a hormone imbalance. Estrogen and Progesterone have to work in the correct ratio to each other in order to have a normal cycle. If you have a sore breast near your armpit, i recommend you see a doctor for an exam and history, in this way he/she can examine the breast and help you to understand why you may be missing your cycle. Best luck, .