Sudden chest acne since a few months

I have been having chest acne since the past few months. They've been painful to say the least and are scarring. I never had chest acne before. There's no change in my routine other than the fact that I've started working out actively. I use clindamycin phosphate gel for my face acne as well as this but it never ceases to exist. Also i am on isotroin 20mg. But my chest acne and face acne are not reducing. What to do?