We bought a shelter puppy at the end of July. He is a mix breed of Hound,Lab and who knows what else. He was born on May 13th so he is just shy of 6 months now. My kids have wanted a dog for years and we finally gave in, only to have issues with him. Had to take him to the vet right away he had every kind of worm a puppy can get. After that was cleared he received his shots along with Sentinel and Heartguard around the 2rd of August. Around the 10 th of September, we noticed he had starting shaking his head in an up and down motion, sometimes falling over in the process.Thinking it might just be a puppy thing we didn’t think much of it, but it has continued. So we looked online and thought maybe the flea medicine was to blame so this time we just gave him heart-guard. Still didn’t make a difference. Took him back to the vet to have his ears checked, they were fine. So they did blood work, all was good besides his Phosphorus levels were a little high. Told me to check his food and make sure no recalls or issues with the lot number. Did all that, everything was good. So now he is on Antibiotics for 14 days to see if that will help. He is still doing the head shake. Started looking into everything we have used on him, came across the Hartz post..but we didnt use the flea and tick. We used Extra Gentle, soothing oatmeal..could this be the reason?