Frank, sweety, there you are..

Avonex is aa interferon drug, much like Betaserun and Rebif. They can all cause you flu like side effects, that, go away after awhile for some, but not for all peeps. I had to get off of Avonex because of the high fevers I got, that wouldn't go away.
Since your Neuro has deemed you SPMS, I question his choice of Avonex for you, since it has not been found helpful for SPMSers..
Some SPMSer have tried Betaserun or found some help with Rebif.
Good luck and let us know how it goes for you..