What Causes Pain And Stretching Sensation In Uterus While Having Ovarian Cysts?

I had an ultrasound done during the summer of last year and found out that I had cysts on my ovaries. It has been a while since I have felt any symptoms but now I feel a stretching in my uterus and slight pain on each side, more so when I lie down. Also there is a chance that I may be pregnant but I believe it is too early to tell due to the test still displaying a negative result. Could this be due to early pregnancy or the cysts growing? THANK YOU IN ADVANCE FOR YOUR RESPONSE