Call your local vet and see what they suggest. Maybe they will say you don't need to take your dog in and can give you some advice on how to take care of the problem. I would take the dog in if it were me though. Maybe the dog got bit by a mosquito, stung by a bee, bit by something, or he/she got into something that he/she shouldn't have. Your local vet can give you the best info. and advice on what to do. Good luck to you and your dog. That is sad, I feel for your poor dog. I hope he/she gets better soon.
This dog needs to be examined by a veterinarian. Allergic reaction to an insect bite can lead to periocular (around the eyes) swelling. Conjunctivitis and an ocular foreign body (like a foxtail or piece of grass) are also possible causes. Your veterinarian will make sure the globe is intact and stain the cornea to make sure there is not a scratch or abrasion. I would have this dog examined soon-especially ocular disease can be very serious.
The same thing is wrong with my dog but its summer it could be allergies or my dog scratching its eye to much so...!!!!