I lost a part of gums after from Zoom Whitening? (photo)

I had Zoom teeth whitening 10 days ago.Apparently, some solution seeped under the protective gum coating and left a nasty burn on my gums. in the beginning it looks like a blister or an ulcer with a dark color and after 3 days it took a white color and then it became yellow , in this stage it extracted and left my teeth without a cover and that make them so sensitive and even now after all that there is a small white spots so please tell what can i do and if the gums gonna be recovered .