I've got some discolouration on my eyelid i'm 36 and worried ?

See a doctor: You will need an examination. Have a look at these images however and see if any look like yours for an idea of what it could be. http://www.dermnetnz.org/topics/eyelid-skin-problems/

Lid discoloration: The correct answer depends on whether it is a pigment color change or an inflammatory color change or some body dysfunction that is causing this appearance. An ophthalmologist can alleviate your concern.