What Does A Hypoechoic Area In The Endometrium Mean?

Hi, I am a 40 year old woman, 163cm tall and 95kg with a history of ovarian cysts, CIN3 cervix issues resulting in a biopsy, previously diagnosed with polycystic ovaries. My first period was at age 10/11.
I recently had an ultrasound which indicated that I have a hypoechoic area within the left side of the endometrium which is mildly thickened in comparison to the right. I have been having abnormal bleeding/discharge (which smells bad) between my periods for the last six months and been suffering from nausea, moderate to severe pain in my pelvic area, sore breasts, needing to go to the toilet more than usual and being tired a lot of the time. My GP doesn't seem too concerned but I was wondering if you could shed some light on what a hypoechoic area is and what I should do?