HELP ME!!

Okay okay, so I need help. I may have a yeast infection. So two-ish weeks ago I got really sick and ended up taking a lot of antibiotics, I maybe took too many. So now my vaginal pH is haywire and candida is like "yay" ( -_-) and I didn't realize cause I thought it was just the smell stuck in my nose (I work with yeast in the lab, sacchromyces not candida) and so I didn't notice that I only smelled it when I peed. So now that I've reached this conclusion, I'm going to go buy monistat tomorrow, do you recommend a one day treatment or seven day? Also I was supposed to get my period yesterday, still haven't. Does this infection have anything to do with that or am I just late like normal people? Will the one day treatment fix it? I can buy two and make it a two day treatment just to make sure that I've properly gotten rid of the colonies. Any advice would be appreciated because honestly this is the first time something like this has happened.