Hi I Have Been Getting Red Marks Of My Stomach

hi i have been getting red marks of my stomach area only but when they go away they leave very dark marks and more come ,and now my whole stomach is full of bruised like marks..;( help.what could ot be?should i be worried? and how do i get rid of this? i am embarrassed to wear a bathing suit cause it looks like i have been beat..please help me to understand what this is