dont whatever you do pop it. i used to work in an industrial kitchen and bunt myself pretty much every day and have loads of scars from burns. just leave it be, the blister is your bodys own natural healing system, just take care aroun d the blister and try to makesure it doesnt burst. also keep it away from heat as it will hurt like hell. just give it time and it shoudl go down. sunno how big a nickle is being from the uk but ifts a coin thats tiy. ive have huge ones on my arms and the scars are now nearly gont after 4 years. it'll be fine.