This lump is very painful to the touch. Is this something I should rush to the doctor for, or is it OK to wait? I don't have insurance.
You can get a pimple on your nipple, just like you can get one on your forehead or nose. Your nipple is filled with Montgomery's glands, small oil glands that keep it supple; and these glands can become blocked, and develop into what's basically a pimple. Aside from an oil gland becoming blocked, you could also have an infection in a milk duct, which would be somewhat more serious.
Give this issue a couple of days or so; if it doesn't seem to be getting better, then yes, you should go to the doctor and have it treated, as you'd want to start on a course of antibiotics. Or, if it gets worse (your breast becomes painful, inflamed, red, hot, swollen, or itchy), then see a doctor ASAP. In the meantime, try applying warm compresses; and DON'T squeeze the bump, OK? That could cause any infection to spread and become worse.
Ok! Thank you so much for your help!