Sounds like he has a bad ear infection which may be causing a lymph node to swell.
Those can be slow to heal.
If you are seeing improvements, I'd keep up the good nursing care and give the meds a couple more days to work. Ear infections can be slow to clear and ear pain as well as infection can make a dog feel pretty awful.
If the Petsmart vet is open tomorrow or Sunday I'd suggest you check back in with them over the weekend if your dog isn't seeming any better.
You can read about ear infections here
Hope this helps you!
I forgot to note that his eyes are red and he is having trouble seeing. He can see but I think that since his eyes hurt he keeps them closed to make him feel better.
If you are now seeing eye issues then I'd get him back to the vet poor guy!
You can at home rinse them out with sterile saline which may make them feel a little better.
With eye problems its best to get in person vet care again.
This may be a part of the same infection or it might be due to the eyes being short on tears causing a sore on the cornea etc.
You can read about conjunctivitis infection here
Dogs do not get human flu, they don't get mumps and its unlikely eating a non food item would cause ear infection and eye problems.
If he has not completed his shots distemper is a possibility
Is distemper curable? Is it curable with antibotics or will the medicine help him to health? After getting his shots will it go away?
Do please read the information on the links provided as that will answer a lot of your questions.
Only an in person vet can make a real diagnosis so you need to see a vet again with him.
Shots are preventions not cures. They keep a dog from getting dangerous contagious diseases by teaching the immune system how to fight the infection. They don't help once the dog is sick.