Im tired all the time and going to urination often,plus pain down my lower right side. i had a full HST.?

doctors all say cant find anything,but im normally an active person,so for me to be tired all the time,plus going bathroom to much and pain down there is not normal.i had a full hysterectomy already due to ovarian cancer and painful cysts on ovaries,so why am i still so tired and in pain.