Going through a bit of a crisis and need quite a bit of help.

I was offered a promotion at work recently. I had never thought of being in the position offered and never really thought of myself as working in that sort of position. Everyone pushed me to take it even though I didn't really want it. I understand it'll look good on my resume and I wanted more of a challenge but I really wasn't leaning toward accepting it. Though I only had one day to answer and I ended up taking it.

Now I see it's far more intense than I thought it was. Everyone says I'm doing fine but I honestly don't really think it suits me. It's far more fast paced than I thought and not at all how I like to work or tasks I like to do. I'm overwhelmed by the stress and pressure of the position and my fears about the position when I was considering to take it or not seem fairly valid. I can do the actual tasks and they're slowly starting to make sense but the intensity of it all isn't working for me.

I wasn't given any salary information regarding the position (even though I asked) as management wanted to wait and see what happened in the first 90 days. They did give me a small raise in the interim and said I could take my old job back and keep that raise if I chose to. Problem is I don't want me taking my old job back to be used against me and my old job was honestly the other end of the spectrum- a bit too slow.

Basically I don't know what to do in this situation. Everyone just keeps telling me to do it, don't look back, it's bad to go back to your old job... but I can barely sleep at night and I honestly don't feel like I'm handling it. Ideally I'd like to find a job more in line with what I like and that fits my personality but I'm trapped in this situation.