Black Laborador - just turned 6 years old

Question
My black lab male (Blackie) is 6 years old.  Starting around Labor Day of this year, he gradually slowed down eating his dog food.  Now he has completely stopped eating in the last 2 weeks.  We took him to the vet and somehow has an infection (runny eyes, cough) thru bloodwork.  He is on antiobotics right now and has about 1 more week of taking them.  He has not been neutered (I know my husband's mistake) and he is very depressed, low energy and I want to say "pouts" with his chin down when he lays down all the time.  He seems to sleep a lot.  BUT, he gets very excited when my husband wants to take him for a walk (he perks up right away).  He smells every where AND goes to the bathroom in every spot he sees.  I've done some research on the internet about dogs not being neutered.  I'm wondering IS all of this from NOT being neutered (his behavior)?  By the way, when we took him to the vet, the doctor checked his testicles and one of them were large in size plus "soft."  Is this a sign of cancer?"  Any help or thoughts would be appreciated.

Answer
Try e-mailing this guy. truebred@tpg.com.au Hopefully he can help. It could be testicular cancer,prostate disease or hernias, hyperspaysiait, or a swollen epidimus. after HE RECOVERS I WOULD RECOMMEND GETTING HIM NUETERED. remove it and have it tested at a labratory. talk to a different vet pronto!!! go to justanswer.com/dog