Does monistat 1 (tioconazole) day work for yeast infections and if i use it and it doesn't work can i immediately start using monistat 3day?

Works immediately: Technically, Monistat 1 (tioconazole) day should work immediately. If it doesn't, Monistat 3 day may be required. If that does not work, it's either not a yeast infection that's bothering, or it is a type of yeast that is resistant to Monistat.

Yes: It won't hurt you to use one after the other. If you don't feel better, you may need an exam to make sure this is really a yeast infection. Also, some types of yeast are resistant to standard treatment and require a different medication. Best wishes!