Help?

I'm 3 almost 4 days late for my period and I've been having strange symptoms. I'm tired, I keep having full cramps that don't feel like regular period cramps. I feel super bloated and am super gassy.  I keep having random moments where I have to run to the bathroom tampon in hand because i swore it felt like I had just started (tmi sorry). I took 2 tests that say negative. Can anyone offer any suggestions?