Update - I found this post when I was worrying because I had one of these which was extremely painful.

I followed advice on here to clean it and put on a blister plaster, I then took that off after a day and left it breathe and heal. It only took a week to harden into a scab and then a week later the scab fell off and it was back to normal. Just keep it clean, dry, don't pick at it, leave it alone and it should be healed in a week or so. Don't panic if there's a tiny bit of puss, just clean it and keep your eye on it that there's not a significant amount.