My Rash Is Getting Worse. Remedy?

i have been haveing iv antibiotics thro my pic line and developed a nasty rash,thought it would be allergy to the antibiotics so it was changed to another one they flush my line each day with heperin my rash is getting worse each day , some look like welts others red with white middle i went to hospital they seem to think it allergy to antibiotic,, i think it could be the heperin after reading about it,,still have pic line , nurse coming to flush with heperin , but rash getting worse each time they do it/