I have a 10 year old springer spaniel/black lab mix and she was always very healthy until now. She is lethargic (she's always been a little lazy but it's much worse now), has excessive discharge from her eyes (it is usually clear but also turns green and gooey), her nose is almost always warm and usually dry (it used to only be like that in extreme heat), she coughs a lot, and her eyes are red. I took her to 2 different vets 3x now and it still seems like something is wrong with her. The first 2 times to the vet they looked her over and said she was ok. The second time they said we should do a blood and urine analysis but again said she was ok. Now I took her to a different vet and they said she may have a sinus infection but really did not seem like they knew what was wrong. They seemed like they agreed something as wrong tho. I am giving her some antibiotics now but that's all and it does not seem like it is working. This is becoming frustrating. What could be the problem?

Sound slike you need to find a new vet. If any animal has a discharge like that, Something is definitly wrong. If they prescribed her antibiotics, what was it? How long has she been on it? Antibiotics take time to work and must be given at the same time every day to be effective. Have you called your vet to tell him you don't think that the antibiotics are working? If so, what was his suggestion?
If it wasnt much, You definitly need to find a new vet.

I live in a very Rural area and have access to 2 differnt types of vets. I use one for our basic vaccinations, Frontline and heartwormer as he is close and less cost then my other vet who does our health testing & checkups.

Some vets are old fashioned and some are more up to date. Just because you feel like you already have a vet, doesnt always mean he is the right vet for you and your animal.

Good luck..