Girls, hello! Such a question! Please help me, I can't understand... I...

Girls, hello! Such a question! Please help me, I can't understand... I have an ovarian cyst, it wasn't a couple of days ago, ultrasound showed size 4.5 today I went to gynecologist, he just looked but didn't do an ultrasound said the cyst decreased 3-3.5 as in a couple of nights could she decrease that much? Two days ago my period ended today before going to the doctor again I went a little bit but something bothered me that my period was like water, watery and dark! Here I sit and think maybe this was a cyst rupture!? Maybe that's why it decreased, came home started sharp pain 3-5 minutes and went now worrying about