Burning Nipples!

Can anyone help me. I had sex a week ago. I wasn't on birth control. I didn't start my pack until Sunday and we had sex that Saturday before. So for my January cycle I never actually bled. I bled when I wiped but that was it. And now here lately my nipples have been burning like they are on fire. Does anyone get that before they start? Or has anyone had it has an early pregnancy symptom? My periods have been very irregular since I had my Mirena surgically removed, so I'm not sure when I'm supposed to start my next cycle. My nipples have never burned before.