My lower eyelid swollen(bump) with a small acne on the eyelid margin(no redness or other symptoms). it is from 2 or 3 months. i used api tobrason eyeliner from 5 days but today i feel it is worsen (slight pain). is it dangerous & what could it be?

A pimple (small acne per your opinion) should not persist for 2-3 months. You probably have a small cyst and it is now irritated either by the eyeliner or it is just a coincidence. You should not use that eyeliner for now, apply warm compress several times a day for a couple days. The lesion may need to be drained if the inflammation gets worse. Sooner or later, the cyst needs to be taken care.