I took macrobid and within 15 minutes developed a hive like rash on my chest. rash hasn't moved anywhere else just stayed on my chest and i don't know if i should keep taking it. it's for a severe uti?

Stop the medication: It sounds quite clearly like you're allergic to macrobid. Hives would be characteristic of that... plus the place on the body (the chest) is quite typically for a drug reaction (as opposed to say, the foot!). There are most likely plenty of other options to treat a UTI -so you need to call your doctor ASAP and get a different antibiotic. Macrobid is often used first - but for you 'never again'.