Lied to my mum about going to work and also lied to my manager about needing to go to an emergency doctors appointment

I was supposed to work yesterday, although I text my manager saying I had an emergency doctors appointment to go to and that I won't make it in time for my shift. He asked to leave a doctors note in the office when I'm next at work, although I didn't have an appointment. Instead, I walked into town for a couple hours with my work clothes on, telling my mum that I was away to work.

It was a sunny day and i was feeling pretty exhausted and stressed, so I skipped my shift. I feel a lot more guilty telling my mum I had work and pretended to go in than I do about lying to my manager though.

I'm not sure how to work around this situation, as I have a shift on Wednesday and don't have a doctors note to show proof to my manager. I also fear I'll get fired and I don't want to make another lie to my parents about why I got fired. I know this is my fault and that's not a valid reason to skip work, but I hate working there.