are you on any new medications? read leaflets for any eye effects.
any other medical issues, with bones, or muscles, or BP etc?
and i have an occasional achey eye, i feel the need to press on it to 'relieve' it a bit. ive been checked, and had scans and nothing wrong with the eye itself - though i do have hyperostisis, frontalis interna, which is thickening of the forehead bone, so i personally think its possibly just minor pressure increases in the socket.
there doesnt seem to be a particular reason for it starting to ache though, just random - but there are things that could irritate anyones eyes - such as tiredness, raises in bp, bright lights, noise, allergies etc.
im on medication that causes dry eyes too.
keep a diary of when its bad and what you have done, or taken, and all symptoms and you may narrow dow what sets its it off. and also note the changes, when you take things like anti histamine, eye drops, even nasal douche etc.
hopefully yours is like mine, and just one of those things that anyone can get - but regardless, definitely see your doc, since you already have a pretty serious eye injury it may be something more serious.