Hello ma'am and welcome.
Well with the description provided this could be a number of things, a hormonal
imbalance, a uterine abmormality, an abnormality of the inner lining of the uterus
. Please visit your doctor for an elaborate evaluation including a speculum examination, a blood investigation to check on your hormone levels, ultrasound
examination, etc. Please do not wait any longer as it seems to be affecting your sex life.
Hope this helps.