Suggest Remedy For Dark Spots Due To Insect Bite

Hi I'm Sal, I have this kind of red spots in my skin it looks like a bite of a bed bug or insect and it very itchy..I'm kinda worried cause after fews days the red spots turns into black and my friend told me use dexa cream to remove the dark spots.Please help me how can i get rid of this cause it so visible in my skin.. Thanks