A question about a hysteroscopy?

I am 51. My periods stopped a year ago, but in January I had a period so got checked out. The doctor said I had an enlarged uterus and sent me for a scan. The radiologist said there were no fibroids, but the womb lining was enlarged. There was a strange puckering to my womb, and seemed surprised I hadnt had a blood test. I am now booked in for a hysteroscopy. It has now been 2 months since I was diagnosed as having an enlarged uterus, and waiting for the hysteroscopy is making me really worried. I have zero energy, and sleep a lot, and have a pain in my lower back (right) but only when I sit in a soft chair (i.e. when my spine is curved). I realise it may be cancer....but of what....ovarian, womb or what? And if not, what may be causing these symptoms?