Charlie,
I had a 2 level ACDF in January and experienced much of the same pain you did. It was very distressing to me because I was sure I was going to be up and working on the computer in 2 weeks, HA! I tried and had the worst headache of my life. My doctor told me I would not be able to return to work for 6 weeks. I did not believe him. I thought it would be much earlier like 3 weeks. Thinking I would be about back to normal after 6 weeks I scheduled a trip for work in which I would be presenting all day for 4 days straight. After week 3 I realized there was no way I would be able to do that. When I had my 6 week check with the doctor, I told him there was no way that I could go back to work yet and without blinking he said do you have more time you can take? Ok see how you feel in two weeks and if you need more call me and I'll write the order.
Everyone is different but the doctors never can tell you how you will react. When I expressed concern to the nurse that I was still in pain, she said it takes about 18 months for the fusion to be complete and while the pressure has been removed from the nerves, they are basically regenerating or re-energizing so you pain may actually get worse before it gets better. that explanation really helps understand it. Here I am 3 months out and I still have pain, much less than before but not pain free yet. I saw my surgeon yesterday and just got released to go to therapy.
Hope you are feeling better every day, but don't push yourself. That is how you reinjure yourself.
I can tell you from personal experience that a month is no where near enough time to recover from this type of procedure. It's going to take awhile and you're going to need Physical Therapy to get those neck muscles back in shape.
It is totally unrealistic to expect to go back work in a month after having a 3 level ACDF. Did your Doctor tell you that you'd be able to go back this soon?
Recovery will take a while, but it will come, try to hang in there.