Hi,
It is a complicate way to answer your question or to get a clear diagnosis with just the data you share. It would be very important to know your age, your sex, pathological background, hospitalizations, surgical interventions recently, drug use (including legal drugs), family history of inherited diseases.
Also it would be important to know the presence of another symptoms, like
fever, headache,
nausea or arthralgias. It is very rare to see an
allergic reaction to cardboard, but it is not impossible. Allergical reactions start the eruptions on chest and back, and are itchy the most part of the time.
I suggest you get a complete hematology to start and take some aines every 8 hours plus an antihistaminic type
Loratadine every 12 hours for 5 days.
Hope I have answered your query. Let me know if I can assist you further.
Regards,
Dr. Luis Alberto Urdaneta Arenas