CRAMPS NO PERIOD?

I've had no period since sept 16 which was my last period and some brown discharge in October (don't remember date) the discharge only happened one time when I wiped, I thought my period would come soon and nothing?? Took 4 pregnancy tests and all were negative...but here I am today wondering if I might be pregnant after all I'm having major fucking cramps, back ache and no period I've been like this for two days usually my period would've already came with the symptoms I feel. I have two children but each pregnancy was completely different! I don't have any sore boobs but I do get headaches.

I had given up on the possibility of even being pregnant because I had a nurse visit but my pt came out negative once again they asked me to go back after thanksgiving weekend to retest if I still didn't have a period.

I don't want to spend on another pt! But now I'm afraid that I might actually be pregnant!!