Need help

Me and my boyfriend have need trying for four months to have a baby. Recently I started my period six days early, have bad abdominal pain, black period blood and frequent fluxuating fevers. I went to the ER, they did a CT and an ultrasound and sent me home with no answers. I don't know what's going on and I'm scared that I am infertile. Any suggestions or guesses will help. Thank you.