Used Baking Soda On Face After Fraxel Treatment And Now Have Dark Red/Brown Spots

The fraxel laser treatment went really well and it was only my second one. I am just not sure if my skin was still too sensitive from the fraxel laser treatment to try the baking soda.

I recently had a fraxel laser treatment done for my cheeks 3 weeks ago to get rid of minor acne marks and minor scarring. A few days ago, I tried using baking soda mixed with water as a paste for my face after reading some positive reviews on it. I must have massaged it into my face and left it on for too long because it left my face stinging read for the entire day. Now, a day later, I have dark reddish brown spots on my cheeks that I did not have before. Are these just burn marks that will eventually go away? Or did I ruin my face completely and now have permanent brown spots that stained my face? I am 18 years old and Asian.