My skin marks/scratches really easily. why is this?

Not sure of question: You may have a condition know as dermatographism or "skin writing". This is a skin disorder seen most commonly in young adults (20-30) & it is the most common types of urticaria, in which the skin becomes raised and inflamed when stroked, scratched, rubbed, and sometimes even slapped. I recommend a proper evaluation & treatment (if needed) by a dermatologist.