What Causes Hard Lump On The Corner Of The Eye?

Hi. I had surgery to tighten my lower eyelid as it was tearing a lot, I got celulitis after the surgery which has now cleared after massive doses of antibiotics, iv and oral, i am left with a hard tender pea sized lump on the corner of the eye, whar could it be? and will it go?, thanks, I am 55 weigh 11 stone and am 5 feet 7 inches. I have crohns disease which isnt a problem at the moment