Hi! I Just Got Out Of A Relationship And Haven't

Hi! I just got out of a relationship and haven't been sexually active for 2 months. I have had a steady period until this month. I'm now 15 days late. I took a pregnancy test and it showed up negative and I have had PMS signs such as breakouts, sore breasts, light cramping and bloating. I have also been sick with a cold and been out in the severe heat (don't know if that affects a period).
Also, on the day I was supposed to start there was light blood (one time)after I used the restroom as well as cramping. The day and the day after I seen the light blood I was in extreme heat and walked a lot.

Please give me some insight on what I should do or what could be going on.