Is it normal that I am incredibly sensitive to breaking out when I have chocolate on my period?

High sugar and fats, as well as dairy, can increase chances of acne due to inflammatory responses. It’s probably not the chocolate causing you to break out - it’s probably the sugar or the dairy. Also, don't forget that your hormones change during your period as well which could increase your skin's sensitivity to acne. Always check in with a dermatologist if you have issues related to skin!