She might have something in there, i.e., dirt,piece of food, etc. Or it could be infected....like we can get "pink eye", I believe they can too. And if you've ever had pink eye, you know it bothers you, and that is why she is squinting. When you take her to the vet, he will be able to look in there and see what's up. I wouldn't keep bothering her with it. One time, my little Sierra had a pebble in her eye. It was just sitting in the corner of her eye, and when she looked sideways, I saw it. I couldn't believe what I saw! Of course I got it right out and then she was fine. She never complained, and if I hadn't seen it on my own, who knows what would've happened!! It was about half the size of a pencil eraser top. I can't imagine how she got it in there. We live out in the country, and we have a lot of gravel, but I am always with them. I figured her sister, Chewy, was doing the "potty dance" and she must have been in back of her and one flew in there. Phew! That was a close one!
Good luck with your baby and she is in my prayers. I'm sure she will be alright!
