Pelvic pressure and bloating. Period late NOT pregnant.

My period is 4 days late and the past almost 2 weeks, I have had tons of pelvic pressure, bloating, lower back pain, some constipation and gas pains. I went to the doctor and she told me my bladder and uterus had spontaneously prolapsed and is sending me for an ultrasound Monday. I am TERRIFIED of what they are going to find. I made the mistake of googling and obviously all this scary stuff came up. I do have a history of ovarian cysts in the past, so I’m trying to think logical that it is more likely to be that but I’m still panicking. I took 2 pregnancy tests that were negative.

Has anyone else had this? My periods are typically pretty regular. I’m uncomfortable and worried.