Freaking out!!

hi, ive got a patch on my skin that i've had a while. causes no pain or discomfort which is why i easily forget its there. it seems to be purple in colour depending on my circulation. ive always had sensitive skin i.g dermotisis. well ive only just decided to look it up. however the results aint good. its not chanimg in size or anything. im super scared. its smooth and looks abit like a birthmark. Anyone experienced this?

thats a bruise, even if you cant remember bruising it, or even if it isnt painful, its just a bruise.

ive had it about to years!? i noticed it once when getting out the shower. never concerned me at the time. if im cold its more noticeable!! it fades when i touch it etc. its never itched.

two years