Poor Tank! That rash looks pretty severe. It could be something like an allergic reaction, scabies, flea allergy or a severe case of puppy pyoderma. Because there are several conditions that can look like this and they all require different treatment, I recommend to take Tank in to see his veterinarian. The doctor will examine him and try to determine the cause for all those lesions. It’s likely he will get an anti-inflammatory and antibiotics. If parasites are suspected, he will get a treatment for those as well. I hope this is helpful and please feel free to post any additional questions.