For about two and a half weeks my breasts have been swollen and ache. Lately, my nipples have become extremely sensitive. To the point bras are uncomfortable due to size, and the fabric against my nipples. My lower back aches, I cramp periodically, but I'm not supposed to have my period until next week and I haven't been bleeding. I also have a reoccurring headache that won't go away and for the passed week I've been making frequent bathroom trips. My boyfriend and I have sex regularly, and there have been a few times we didn't have a condom with us at the time. I took a pregnancy test, but it came back negative. Could it be wrong? And if it is, what could be the cause of all this?