Wasp sting

Last night I was asleep, I went to roll over and rolled right onto a wasp and got stung!

 I was told to put a banana skin on the sting to take away the itch, didn't work

 Let swelled up and itches like crazy, I put vinegar on it to take away the itch, it helped 

3rd day it turns black and blue, I put arnica on it and it helped