It sounds like the dog may have an intestinal problem and could have a problem with the nerves in his face area called Horners' Syndrome. You can read about this here
www.petcaretips.net/horners_syndrome.html
It could also be your dog has an eye infection or is suffering from having been hit by a car etc.
The dog needs vet care for both problems.
Your husband is wrong about the pain as dogs often don't show it easily and at the very least the diarrhea is hurting him.
Please get your pet to a vet.
Hope this helps you!
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