Anyone else used this product? I used to give my dog Bravecto chews but after awhile he hated the taste and next day vomited from it. Vet suggested I try Bravecto Spot on. Applied it 1 month back and is meant to last 6 months but poor guy has been scratching a lot last few days. Booked him to visit vet but not sure if it is the Bravecto causing him to itch or it has not worked properly and poor guy has fleas.