I was prescribed nitrofurantoin 100 mg to take every 12 hours for five days. I am on the fifth day and have one dose left but it is clear this antibiotic is not working and my doctor has prescribed a new course of antibiotics for me( sulfamethoxazole- also 1 pill 12 hours apart for 5 days) I am assuming I should finish that last dose of the previous course of antibiotics before switching to the new one despite them not working, but do I start the new antibiotic 12 hours after my last dose of the previous course or should I wait for longer? I’m sorry if this is a stupid question it’s my first time dealing with being resistant to an antibiotic or having to start a new one so soon after the previous course.