M.F.
She's had a rash for 5 days now? I would definitely take her to the doctor ASAP. Any symptom that lasts for 5 days is something that should be checked out. Does she have any other symptoms like fever? If it was me, and I'm not a "run to the doctor" kind of mom, I'd take her to Urgent Care today instead of waiting until Monday, just in case it's something serious like chicken pox and especially since it's lasted so long and keeps getting worse. Worst case scenario, it's something totally minor and you wasted a few hours. Good luck!