Like others have mentioned I would speak to a Vet first. However my pup has really bad allergies (both food and plants, pollen) and I've found that tea tree shampoo works great. The one I used is by John Paul called, https://www.chewy.com/john-paul-pet-tea-tree-shampoo-dogs/dp/40915?utm_source=google-product&utm_medium=cpc&utm_campaign=hg&utm_content=John%20Paul%20Pet&utm_term=&gclid=CjwKEAiArbrFBRDL4Oiz97GP2nISJAAmJMFao4-Z1ebpSGBAZiG9T7wPlyTuFOD1CJgCRngwYSCo8xoCn_rw_wcB&gclsrc=aw.ds (Pet Tea Tree Shampoo for Dogs & Cats). I haven't tried oatmeal as my dog is allergic to it but that might be a good ingredient to look for too.