What Could Cause Black Spots On The Wall Of The Uterus?

Please doctor,i cant get pregnant so i went to see a doctor and he did a scan,i saw a black spot on the walls of my uterus and he said its a very little fibroid i saw other black spots in my womb,they wer about 17 as accounted by the doctor,he says i have to lose some weight before also he would give me some drugs so i can lay proper eggs,please doc,what is the cause of all those black spts and why cant i get pregnant