Help! I’m so nervous!

I am four months postpartum and today I started to feel a severe pain in my right breast. It has been getting progressively worse, it is hot to the touch and there are some red lines on it. I have a low-grade temperature and I am super nauseous. I never breast-fed. Is it possible to have mastitis? Or a clogged duct? The doctors office isn’t open this late and I’m freaking out.