Well that's a bummer :( it probably IS an allergic reaction. It gets better and less red when cool, so swimming is the #1 way to make it more comfortable!!!! A cool sponge bath is good too. The reaction is only gonna go away on it's own time. It depends on how much she had in her system and how quick it will get OUT of her system. Good luck! Hope I helped ;)
Hello and hope you are doing well.
Local application of mild anti pruritic lotions may help. If the rash is worsening, she may need antihistamines. Also, medications like tylenol can help bring down the rash and swelling. However, if she develops additional symptoms like problems with breathing or rash and itchiness all over, you will need to go to the ER.
Hope this helped and do keep us posted.
The rash/hives should go away within a couple days once it has completely left her system. Obviously, don't give her any more pencillin in the mean time. You can try reducing the swelling and pain of the rash by putting some ice on it. I believe your daughter is too young for Benadryl so this is just a wait and see process. The dr. is wanting you to check to make sure the rash doesn't spread further and doesn't start to affect her breathing...so keep a close eye on her for the next 24 hrs. like dr. said. She should be better by her birthday! Good luck to you and your baby.