Welcome to HCM,
may be due to drugs as you have taken antibiotic and analgesic
which may be cause please stop all the drugs if you have nit stopped, for drug reaction please continue to take antihistaminic medicine and steroids
but these must be taken under supervision of Dermatologist/Physician.
If you have acute reaction then you can be given injectable to get quick relief,but please visit a Physician or emergency room to see and take appropriate action.
If it is due to drug be very careful to take the same drug next time.
Please take care.