self harm

hey guys so i was wondering if you could help me figure out something. i’ve been clean of self harm for almost a year now. however, even when i’m in the happiest of situations I get the urge to self harm. for example, I was shopping today & the hangers scratched my arms & it made me want to relapse. it was almost as if I liked seeing the marks on my skin. can anybody explain to me why i’m feeling this way? it’s just really odd for me to be happy but also want to cut myself