The swelling you have on your left eyelid is called a Hordeolum. Every eyelid has a row of glands on the upper and lower lid margins and a different set of glands on the inside of the upper eyelids. These may , at any time, be subjected to blockage and infection causing the gland to swell with a subsequent symptomatic presentation of redness , pain and swelling. Which set of glands are affected can only be determined by an eye examination but in the acute stages, which is what you have, the treatment for both stays similar. Hot fomentation directly on the swollen area with the eye closed using a washcloth soaked in warm water and squeezed works very well to relieve pain and soften the swelling therby aiding faster absorption. This has to be done twice a day 15minutes each time. Use an antibiotic eye ointment in your eye as well as on the swelling. Chloramphenicol eye ointment in the form of an ointment tube or applicaps works well 2 times a day. If the pain is bothersome , you may take Ibuprofen or paracetamol tablets to lessen the inflammation and pain. Refrain from pressing the swelling to burst it as this may easily spread to the delicate surrounding skin leading to a more generalized inflammation. In many instances , the swelling subsides with treatment but in larger swellings and of longer duration, the pain and redness subside but the lump may have to be incised and the cheesy, pustular material removed manually.