I can only imagine how painful that must be. Also opening the eye must be very difficult. From your description it seems like a stye. In easy terminology it could have happened by extensive rubbing with an irritant in the lashes or a lash infection.
Next Steps
Do not rub the eye please. Try cold fermentation, place an ice pack wrapped in a soft face towel over the eye.
Anti-inflammatory will definitely help in Pain as well as reduce inflammation. tab Brufen 400mg twice a day may reduce your agony.
normally a combination of oral antibiotics and topical ones bring the situation in control early and easily
Health Tips
please don't randomly start an antibiotic, have the eye checked out and then start.