Can anyone tell me what's wrong with my vision?

this has to do with my right eye (not that it really matters) But, its always been my less dominant eye. i joined the military and ended up having to shoot left handed because i could not see well at all (with gles) down the sights of my rifle. when i close my left eye to shoot or to...wink at the ladies?, its very fuzzy, and when i focus on things, my vision goes black. sometimes, it hurts, most of the time not. As anyone could guess, its very bothersome. ive looked into cataracts, as well as glaucoma, both have small indicators, but i feel like they both are not whats wrong. i hope im not losing my vision. And id like to get an idea of what it is before i take it to a physician, due to my military status as i dont want to get discharged. foolish, some may think but :D i hope everyone understands. its my life. any help that you all out there could offer would be great. thanks everyone!