Taking Monistat 3 day

I know you’re supposed to have it checked out by a doctor before hand, but will it do anything harmful to use Monistat for a yeast infection if you don’t have one? I’m 98% sure that I do have one though. Currently on day 2 and it does feel better than it did before, but I read reviews that it’s supposed to burn after injecting the suppository and it’s not burning to me. I’ve had this issue (itching/ additional white discharge (no bad smell to it)) for a while and I believe it has spread to my anus because it itches as well. TMI, I know. And no, I do not have any kind of sexually transmitted disease. I have had a test before.