What Causes Soreness And Burning In Vagina After Taking Treatment For Yeast Infection?

I am 18, I am 5'4", I weight 153. I had strep throat December 14 and 15, but was given a shot of penicillin to cure it. This caused a yeast infection for me, and after not being able to reach my doctor for three days, I took an over the counter medication for yeast infections, which was sort of like inserting a tampon full of medication into my vagina and leaving it in over night. I think that it caused the yeast infection, because my vagina returned mostly to normal, although it was a little itchy, but this is a side effect of the medication. I got my period and today was the first day without it, and now my vagina is very sore. It is dry and burns upon touch, but not during urination. What is this? What can I do to relieve or cure it?