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It sounds like she is having an allergic reaction and we may never know what she is reacting to. If it is the antibiotic, then she may continue to have a reaction until the drug is out of her system. If the new antibiotic is in the same class, then it could cause the reaction to continue. It may also be that she is being re-exposed to the allergen such as a contact allergy from grass, plants, laundry detergent or even certain types of material and fabric. If she ate a bug then it could also cause a prolonged reaction. It is not uncommon for allergic reactions to last for 3-5 days. You can continue to give benadryl during this time and if it is not working as well s we want it to, then a short course of an anti-inflammatory dose of prednisone may help.
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