Sometimes when your eye dries out from wearing your contacts too long your contact will latch onto a small layer that covers your, well when the contact dries out it can tear that small layer off sometimes which will cause light sensitivity, redness, and some pain too. If this happens all you can really do is wait for it to heal, you can go to the optometrist, but all they are going to do is give you an eye drop that relieves some of the pain and takes away the redness, other then that all you can do is wait for it to heal really I would suggest trying to wear sunglasses as much as possible when this happens because at least even though it does not completely stop light from causing issues with your eye, at least it will help somewhat.