What Causes Heavy Periods,back Pain And Headache?

im 44 years old. I have unprotected sex. The next day or the 2nd day I have my period (heavy) I dont know is was the new of my father death. I took 2 pregnancy test (negative) but my belly keep growing. the only thing that i have is back pain, and headache and tingiling in the uterus. May be the baby is dead or I having a miscarriage. I have 2 already.