eye problem, now sleepiness

Several months ago, my rooster had a problem with one eye. He kept it mostly closed for a few days, then slowly began opening it more. After a week or so, he didn't keep it closed, though I believe he can't see as well with it, but can see. No swelling, no puss, no obvious injury. A few days ago, he started the same thing, with the same eye, but added the symptom of being sleepy. Not lethargic, but sleepy as in he'll nod off throughout the day for brief periods. I've never seen him do it before (I know all chickens do occassionally, but this is a different behavior for him). He's only 2 years old, so it's not simply old age! ;-)

I thought I would try electrolytes and/or antibiotics, or Rooster Booster, but figured I'd ask for any advice any of you may have first. (I've never treated my chickens with any of these things, so advice on product is appreciated too.)

Thank you once again!