Hi, yes I would get the vet to take a look, it could be wasp or bee stings. Is their any sting hole in them, or two? check for a bee sting still in it & pull it out if you find one. Then vinegar & honey on it. My dog had one not that long ago. Also mow the grass so the lawn attracts less insects. Hard to tell from here, but also make sure theres nothing your dog could burn on, like bbqs exhaust pipes etc. sometimes burns swell like that. My mastif x puppy got a burn under her chin from stealing sausages of our hot bbq once!