hello! (registered just for this :)

it is hard to judge from these pictures, but i think ours had similar bumps (they kinda looked like mosquito bites). started with one/two but during couple of days they spread… after quite a quick look veterinarian said that it is allergy, and most probably allergy to grass (not nice if you are a dog). gave us some medicine (i think Medrol) so we gave him a couple of tablets and were good for a month, then it started again. and tablets. and good for a month... it got better in autumn and no problem now in winter (hoping that maybe next year he will outgrow his allergy)

not sure it helped, but... if it doesnt get better, definitely visit vet.