I’m sorry to hear about your fellow Buddy.
Do his lumps look like this?
If so these are probably contagious viral warts (papillomatosis). These are considered a contagious, sexually transmitted disease caused by a virus and contracted when a dog mates with or licks/sniffs a dog that is affected by them. They can be passed by casual contact too between dogs that are playing together or sniffing each other. They tend to be found on the lips, eyelids, inside the mouth, on the footpads, and in the genital area. They are not contagious to people but they are extremely contagious to other dogs. As such he should be kept away from other dogs so out of doggy day care and dog parks.
In most cases these benign tumors resolve with no therapy needed at all in weeks to months. Rarely these can transform into a malignant variant and don't resolve. These need to be removed surgically with wide margins. If the warts are getting ulcerated, interfere with eating or become uncomfortable we can use an antibiotic, Azithromycin, for 10 to 14 days which seems to hasten their resolution.
If you'd like to read more please see this link for an in-depth article about contagious warts in dogs: http://www.petwave.com/Dogs/Dog-Health-Center/Skin-Disorders/Warts.aspx
In short he likely picked up the virus somewhere. Generally with immune system maturity they resolve without treatment, but it sounds like that isn't happening for him. For whatever reason his immune system is not able to control this virus. There isn't any over the counter supplement that will help him unfortunately. He does need to see a veterinarian. But perhaps a fresh eye on him with a new veterinarian would be best if you aren't pleased with how things went with his first veterinarian.
Please let me know if you have any further questions.