Suggest Treatment To Remove Black Marks On Legs Due To Food Allergy

hello, doctor! for past one month, i have skin problem! when i went to clinic the doctor told that, i have alergy of seafood. i felt itchs and my both legs become alots of red dots and turn to black marks. now my both legs have so many black marks? what i can do or which treatment is best for me to become normal without black marks.
tq
awaiting for your advise.