Periods stopped not pregnant

Jenna

My periods stopped my last one was on the finished the 25th of November I’ve had a blood test done at the doctors and it was negative. On the 12 of december or around them I had discharge that was red/pink threw out the day and stopped the day after I keep having really bad cramping which I’ve been hoping is my period pains but been going on a while. Anyone know what could be wrong?