I would take him to the vet to make sure it's allergies before treating it. My girl Robyn gets watery eyes and it is allergies. Both of our allergies seem to happen at the same time.
Misty- Samoyed Mix, Tannor- Golden Retriever CGC
Robyn- GSD CGC, TC, Midnite-GSD CGC,TC, Brennan-Golden Retriever CGC, Batman-Husky/Greyhound , Apollo-GSD