I hope you have some more time to recovery. Six weeks is such a short recovery time for ACDF. I wish you all the best.
I will pray for your successful return to work. I know what you are feeling. I have my followup on March 3 and will find out if I will be returning to work next week. I do not feel like I am ready yet but we shall see.
Yesterday went a bit better, but I am still so fatigued at night and get such burning pain in my shoulders. The increase in nerve symptoms freaked me out. I am determined, though to see it through. Part of the reason for that is exactly what you said--I want to try and prevent any problems with the disks above and below the fusion. I don't want to have this surgery again!!! I start work on Monday (yikes!) and I'm really concerned about managing getting back to work and having PT as the same time. Next week is going to be tough! Good luck and all the best to you in your recovery.
I also have recently had multilevel ACDF but am only 5 weeks post op and have not started physical therapy yet. What I want to share is that all my research says that completing physical therapy and doing the exercises for the rest of your life is the key to not having problems in the remaining disc. Physical therapy always leads to some pain and discomfort because your muscles have atrophied due to none use. Keep working and communicate with your Dr. and the therapist to manage the pain.