i think you should go to the vet, but thats just my opnion i could be wrong, but he could be having an allergic reaction.
Exactly, I agree with you ! My friend was in same situation and he didn't care to go for a vet or haven't consider any one else even. After some times his dog felt down suddenly while walking, the result was disastrous !!I'd at least call your vet. Sometimes if the reaction isn't bad they can tell you the dosage of over the counter meds to give. They may tell you to bring him in depending on the situation, but even then it's better to be safe than sorry.