Georgie, our Newfoundland puppy (he’s 9.5 months old), has been enduring some itchy rashes on his underside this spring. His vet says it’s allergies. He makes it worse by scratching at the itchy areas.
We came home with a bag full of stuff to combat the problem. The goal is to treat it successfully without depending on antibiotics at this point. So we’ll be using various wipes and ointments and even a food supplement to up the essential fatty acids, and as well we’ll try an antihistamine.
27th Street 
You have our sympathies! We had a yellow lab that had grass allergies and leaf mold allergies that made his ears really itchy! One solution that actually worked for us was discovering he and another Newf had an allergy to red food dye – switched to a non colored food and that really helped as well as a fish oil supplement?
thanks. The combination of stuff the vet gave us seems to be helping already. Georgie has pretty much stopped scratching. Hopefully it will continue to work.