Missed 2 periods!

On Nov. 21, I experienced what I believe to be called "implantation bleeding"--It was discharge with blood, and also toilet paper was pinkish after i wiped. Nov.30-Dec.2 was supposed to be my next period, well i missed it. Then my next period was supposed to be Jan. 5, and I missed it again! I have experienced some things/symptoms: leg cramps, ovarian pain, discharge (I thought i got my period today and when i went to the restroom it was yellowish discharge), back pain (the other night i couldn't even sit up, i had to lie on my side), tension headaches that make me nauseous, bloatedness, enlarged nipples, and small white bumps around nipple and areola. However, Home pregnancy tests indicate i'm not pregnant. How can i even see a doctor if these tests come back negative? Anyone else on the same boat.