I went a year without a period and then began to have periods again. My doctor did a biopsy and a sonogram. I had large fibroid tumors and several cysts. Also thickening of the uterine lining and my uterus was enlarged. My biopsy came back negative, but I had to come in for regular sonograms and a few more biopsies, just to be sure. After a year of no improvement - random bleeding that ranged from a few days to two weeks, spotting to full out bleeding and fibroid tumors that continued to grow, the doctor recommended a hysterectomy. I was preparing to go an a trip, so I decided to wait until I got back. Suddenly things seemed to improve, so I put off having the surgery. Six months later, things got worse again, so I had the surgery. No big deal. It was done vaginally, so I was only in the hospital overnight. Technically, six weeks recovery, but I felt fine after a few days. Couldn't convince my family that I needed any more pampering! lol Never any indication of cancer or pre-cancerous cells.
There are many reasons for your situation and most are not serious, but you definitely need to have it checked out. Good luck and I hope you have a positive outcome.