Search on the internet for the word "pinguecula" -- is it like that?
A pinguecula, unless it causes you inflammation/discomfort, is usually harmless. If you notice it is causing your eye to be dry or red (sometimes tears cannot wash over them properly, so they become sore) then speak to your doctor.
My dad has had one for years, his optician noted it, nothing to worry about as long as he doesn't notice it "growing" towards his iris/pupil.
Hopefully, this is only a cosmetic problem and you'll have to decide if you wanted to have it removed again -- they can recur so this may be what has happened in your case.