I have a bump between my breasts. it feels hard and hurts when i touch it. i don't know if its just a pimple or something else?

Sounds like:: It sounds like a pimple, or an infected sebaceous gland. I would try applying hydrogen peroxide and warm compresses to the area several times per day, if it doesn't get better, then see your doctor for further treatment options.

Likely benign: At 19 the risk of breast cancer is low. But you could have a carbuncle which is an inflamed follicle/sweat gland. Similar to a pimple. Warm compresses to the area will usually draw out the infection but you should see your pcp for eval.