Don't feel bad! I totally understand that guilt, I go through it too. But if you're typically reliable, hardly ever call out...don't feel bad. If you're in pain then you deserve some time to recuperate. I mean, you could go in and make it worse and then you'd definitely have to take time off, you know?
Your shift was canceled and so it's not your responsibility to go in because someone else called out. Try not to feel bad.
Yeah, I've never called out for a shift. I've always gotten them covered a day or two beforehand, never leaving a manager to try and get a shift covered for me. It's like, I do need the hours, and I needed these hours and was going to go in for my shift cause I didn't want to call out and money, but if I don't have to be in, I don't want to get out of bed. I haven't been to the gym in days cause of it, which never ever happens.
Your shift was canceled and so it's not your responsibility to go in because someone else called out. Try not to feel bad.