Hi - Your nipples are very sensitive, so any time they get the slightest irritation, they're likely to be quite painful. There are small oil glands around your nipple, and they do sometimes get clogged, and form a pimple. Try rubbing on some antibiotic cream, and covering with a soft bandage or gauze pan tucked in your bra. If it doesn't feel better in a couple of days - or if it seems to be getting worse (hot, red, swollen, painful), then best to see a doctor, as you may have an infection. And in the future, it's usually better not to squeeze any irritations around your nipples, OK? Good luck - PJH