Never hesitate when it is an eye issue. As greenkouki said... Do a vet visit very soon. In fact, if it was my dog and I had no other options, I would be on my way to my local 24 hour emergency hospital.
Yeah, I don't mess around with eyes. Examining an eye for physical damage takes specialized equipment and endangering my dog's sight because of an incorrect diagnosis or treatment (or lack of treatment) just isn't a risk I want to take.
Vet should be able to take a look to determine if scratched etc.
Vet might also be able to prescribe antibiotic or something to sooth the irritation.
Eye pain hurts and creates sensitivity.
Dog might attempt to scratch or rub on furniture or ground.
Prevent pup from rubbing that eye till you get confirmation of no underlying issues.
Great that you took her in. While viral conjunctivitis in dogs not really considered communicable, bacterially caused eye conditions can be contagious to other dogs and sometimes people. Also, while extremely common and easily treatable, left untreated, complications from a serious case has been known to cause permanent eye damage.
The bottom line for most pet owners that I know (and apparently you also!) is that eye issues need to be looked at professional and quickly.