AA and hives

Hi everyone, my son suffers AA. He has recently developed hives in conjunction with tonsillitis. We changed his antibiotics thinking it was the penicillin. He is recovering well except for the hives, and the doctor hasn't seemed too concerned. They are big welts and flare especially when he is stressed or upset (he is 4yo).

So I'm reaching out to community to see if anyone has experience with this, if there are other aspects or autoimmune conditions that you all may be familiar with should be investigated please. Obviously I would prefer Drs to guide, but they are anticlimactic with getting anything seen as "non-urgent" investigated and sometimes I think they don't know where to start too.