Coming off the pill spotting

Hi im new to all this have friends and family with kids but kinda wanna keep this to myself, my partner and strangers for now. I finished my pill at the end of the 21 day strip and took normal bleed as always but it finished on Monday and I've started spotting 3 days on from then, has anyone else experienced this or know what it is? Also how long in your case if its happened to U did it last? Completely new to this so any advice greatly appreciated. Cheers