What Causes Red And Yellow Circles In Vision?

My name is misty and I ve been seeing round colored circles in the corner to underneath my right eye that in certain light they may change color from red or yellow or even crystal looking. I ve been to two eye doctors and they said there was nothing wrong and even had a mri done all normal but I know something s wrong. I dont have any money to spend please if anyone has heard of this please let me know. Very concerned.