I have irregular periods.my last period was 45 days ago. I am not on any kind of birth control and I think my boyfriend is a cheater but anyway I have had slight pink vaginal discharge for the past 2 days.I feel like I am having a period but no period yet. I have slight menstrual cramps,back pain, headache, slight vaginal itching sometimes,and my boobs are tender.I took a pregnancy test today and it was negative. Is this implantation bleeding or something else?

Take test again. Sounds like your pregnant.

You have irregular periods. Could just be this one is later then usual. Which considering the stress of your relationship right now, dealing with infidelity and the like, that wouldn't be surprising. As well the tests are usually only effect two weeks after your missed period, which gets fun if they're irregular.

The list of symptoms that you described are common in the last first trimester but are more common before your period. Which is to say that those aren't pregnancy symptoms. The best symptom is a missed period. I think your period is on your way.

On to other things. What do you believe he is a cheater? Until this is sorted I would keep him out of your bed. There is a chance that he could drag something, it STI, from whoever he's sleeping with, into your bed and infect you. So Until you have that and your own cycle figure out, I would recommend celibacy.