How To Treat Third Degree Burns On Hand Leading To Pus Filled Bumps?

I have a third degree burn on my hand my dermatologist used liquid nitrogen to remove what he thought was skin cancer it was a age spot I returned to see him a week later and it was dripping a yellow colored substance he just put a bandage on it and said it wood heal a week went by and small pus bumps came up around it and it dripped more yellow colored stuff and itched so I went to my primary care doctor and they told me I had a third degree burn and now have a staph infection. could it also be mrsa? I have been put on an antibiotic could I be contagious?