You have not had any down time for your body or mind to relax & reset. As a result both are turned on all the time. Nonstop. Anything mechanical, if turned on & left on will eventually burn out & breakdown. They all need a turn off, & cool down period. So it is with the human body & mind.
You need to take your down time. Tell these people no. Just do it once. Then do it again. Take your next 7 days off & add a week vacation time to it. That Manager is calling you to come in to work so he doesn't have to step up & do it himself. Because that is what Managers are supposed to do. He's calling you because you aren't married, & have no children to require your attention. It leaves him free to enjoy his days off. He gets his down time for sure. He thinks you have nothing else to do but work. You need to change his mind, because he's taking advantage of you & doesn't even think of finding someone else to do these things because he knows you'll show up.
Been
through this. I've been a Manager, I hated having to go in & work extra because someone called in & there was no one else to come in. But I did it, because that is why Managers are on salary, not hourly, pay. It's their job to do it.
Say no, & take your days off, Roto. You are ruining your health & wasting time you should be able to enjoy for yourself.
WORK TO LIVE. DON'T LIVE TO WORK.