You should see your doctor. They will need to investigate the cause for it. This can be just an allergic phenomenon or onset of some systemic disease.
I would suggest the following:
1) Total and vacuolated esoinophil counts.
2) Erthrocyte sedimentation rate
3) Intradermal allergy tests
4) Serum allergy tests
5) ASLO liter
6) C-reactive protein
7) Antinuclear antibodies
Please feel free to ask if you have further questions.
There are various disease which can present like this. Some connective tissue disorders can present with this. But this can be simple allergy, also. Only personal examination can exclude/conform it. My point of view, is that, the lesions warrant an examination by a physician.
The best doctor would be an Immunologist. But if you don't find one in the near vicinity, see an internist or allergy specialist first.