It sounds more like an allergy, to me. It may be seasonal, or it may be related to the water. Did you change food? Or introduce a new treat they didn't usually have?

If not, I would consider the water as the culprit first thing.

If you do use the Revolution, keep in mind it takes 3 consecutive months of regular dosing of all the pets to be sure you get rid of any and all fleas. One monthly dose will help for about a week or so but the eggs won't be affected.

best wishes!
Sandie