I have a painful bump under my left nostril it so red and hurts if any pressure is applied to it. i have no idea what it is or how to stop the pain?

Abscess: You did not send a picture with this but what you describe sounds like a small abscess which is a part of the skin that has under it an infection. You can apply warm compresses to it to try to make it open and drain but you really should see a physician and get a culture from what is inside if possible and be started on antibiotics. I would go to an urgent care or your own MD ASAP.