So stressed I wanna puke.

I am seriously so stressed out, I'm nauseous.
I just realized I have a yeast infection (which is extremely rare for me to get!!) and monistat is the most excruciatingly painful thing for me to use, so I did buy a store brand 7 day treatment instead. BUT I can't start it till next Monday because I will be out of town all weekend and I already know this will still put me in pain, and I have to keep it on the DL anyways from that side of my family. On top of this, there is a good chance I may fail one of my classes, and I am a 4.0 student, on top of this I am fighting with my best friends who I've ever fought with before. I am so stressed out I am shaking and want to throw up. Does anybody have advice? 
Is it safe to use yeast infection treatment while on my period? Because I will have to start it on my period week (I'm on the pill)