Back hurts from standing too long

Long story short, I’m a licensed hairdresser and I freelance (i work for myself). I’ve been taking this time to try new techniques so I’m currently working on a slow-progress taking a mannequin from a level 2-3 brown to a nice level 9 blonde. I’m doing it in sessions to keep the integrity of her hair. Today I did all over foils on her and my back has been killing me ever since. It only took me an hour to do all foils (with breaks obviously). How do you all keep yourselves busy while pregnant? I’ve never had a good back to begin with, but this just makes it worse.