hi, i have a 5 year old cocker, who had lumps, i thought they were fatty lumps, some were, but the vet had the lumps sent off.and they came back as a lump called sterile panniculitis. it may be worth mentioning to your vet, my dog will have these for life, and we were told this condition could be caused through having him vaccinated, his underlying skin tissue seems to over react. and we get lumps come up.these lumps will not kill him, but everytime a lump comes up it does need to be checked, as if left they can turn into cancer. i hope this helps you with benji, and like i have said it may be woth mentioning it to your vet.but this sterile panniculitis is very rare and not much is known on this condition.
hope benji 's lumps improve and hope it's not what my dog has.good luck to you and benji