Keep in mind your doc obviously has NO bedside manner whatsoever! No surprising, as many neuros do not.
But not an excuse for pushing you off.
You are ONLY FIVE WEEKS post fusion. I can't believe that was your FINAL visit with him? Is he kidding? I know the T levels work differently, but still you are only five weeks out.
You have a great deal of healing to do yet. In fact, you are just really getting going on your bone healing.
I would not get the mindset that this is going to your pain level. Hopefully what you are experiencing is just healing pain.
My fusion was done last april on the lower lumbar and I am still on pain meds, as many folks still are.
If it were me in your shoes, I would call the Neuro back and either schedule a telephone consult with him/her or ask to make an appointment to go in and see the doc. Then to explain what's happening, how you are feeling, and that you feel abandoned by the doc at this point and what do you do? If this doc believes his work is done, then he needs to refer you onto someone, such as a pain management center and/or physical therapy group also to help you regain your strength, improve your posture, etc.. and also to control your pain level.
Hang in there. Force the doctor to communicate with you. Let us know how you are doing.