Good Evening,
I hope the growth was biopsied after it was removed. If not, then your vet did you a disservice in my opinion. I will not remove any mass unless it is going to get biopsied, otherwise what's the point.
Well now what do we do? The mass is likely either a melanoma or squamous cell carcinoma given the regional lymph node involvement and fact that it returned. If it's melanoma, he may be a candidate for the new melanoma vaccine that came out in the last 2 years. If it's squamous cell carcinoma, then surgical removal and maybe chemotherapy or removal of the associated lymph node. If chemotherapy is the option, you will likely notice that those lymph nodes go down within a day or two of starting therapy.
I think it's time you either get a second opinion or go see a veterinary oncologist.
Hope that helps, let me know if you have any other questions.
Dog Veterinarian
DVM, Emergency Veterinarian; BS (Physiology) Michigan State Univ