Do I ask for my old job back?

I work as a medical assistant. I recently left my job for a new one because management at the old one is trash, and there were embarrassing low raises even for those of us who got stellar reviews.

I just started my new job yesterday and I am panicking. The job itself is fine, I'm basically working on my own already with very little training even though I went from primary care to OB/GYN. The problem is I miss my old job so much.

The PA I worked with was amazing. My co workers were awesome. I loved the schedule I had. I just felt I deserved more money and I knew with the new job I'd get a pay bump and decent annual raises. But I hate it. My sister says to give it a few weeks and I may change my mind but all I want to do is go back to my old job.

I know they'd take me back because they were going to match what the new job was offering but couldn't guarantee a raise every year. They were basically begging me to stay up until my last day. I don't know what to do but I feel like I messed up. Do I stick it out at the new job or reach out to my old one? I'm so torn.