Can I delay my period when I'm not on the pill? I need some sort of over the counter medication. I'm due to start in 5 days.

Menstrual cycle. As they say, "the horse is already out of the barn" that close to an expected menses. Best deal with the inevitable, since adding more hormones now may only worsen or prolong the bleeding. Manipulating the timing of cycles requires 4-6 weeks of planning for the best chance of changing "mother nature".
No . no over-the-counter medications to Delay menstrual period.