HELP HELP HELP

sarah L

Normal periods are 3-5 days every 14th of the month. Fiancé and I are TTC. I started period May 15th Have been bleeding for 16 days now bad cramping in right cervix area some days it’s very light spotting some days medium some days random gushes of old brown looking blood. What could this be !?!?! I’ve been on my period for two weeks.