I'm concerned?!

So I went on Antibiotics for my sinus infection and after my 3rd to last dose my vagina started hurting really bad when I wiped or when I went potty and itches like no other, so I figured it's probably a Yeast infection so I got the home treatment with the insert pill thing and I went to go do it and finally got it but when I pulled out the applicator there was blood on it?! My last period was almost a week ago. so why would there be blood?! I've been cramping but I'm still really concerned.