Yes, the best thing to do is get a persciption, but if you are going to do an over the counter treatment, it is better to use the 7-day treatment ones. Yes its a bummer having to deal with it that long, but the one day and three day treatments dont always work that well, As you have noticed. lol. But if possible, i highly recommend just getting an oral perscription because should clear it up in about 3 days no problem.
if the monistat didn't work, I'd call to get an oral prescription...a lot of times you need both to clear it up..