I have swelling lower left eyelid. it is so itchy but not painful. when streched, it has small bumps. what should i do?

Blepharitis: This is most likely a common condition called blepharitis that often causes "stye" or chalazion formation - swollen bumps on the eyelid from blocked glands that may become infected. Try warm compresses and cleaning with dilute baby shampoo, and see an ophthalmologist soon. Most people need a prescription eyedrop or ointment for complete relief, and sometimes a minor surgical procedure.