Personally, I would do a wc today and add some salt as well. What you seem to have is a slight bacterial infection of the tissue surrounding the eye causing "bacterial pop-eye". It's pretty common following an injury or in a tank with less then ideal water conditions. (along with a few other possible causes)
The salt should help quite a bit but you may have to treat the fish with an antibiotic like kanamycin, metro, furan 2, ect if there is no sign of improvement after a few days.