Wow...I started this thread, and never noticed that anyone responded to it!
I can now report that the back pain eventually ceased. I still don't know if phen was the culprit, but it (thankfully) went away. It was some of the worst back pain I have ever expericenced. I get backaches regularly (when I say regularly, I don't mean frequent, just that I do get them. It might only be once a year, but is a chronic problem.
This pain was different though. It hurt no matter what I did. Normally, as long as I lay still, it doesn't hurt, but with this pain, no matter how I sat, layed, stood, hobbled....it hurt!
So, the good new is, no more pain!!! The bad news is, I still have no idea if it was phen or how to help others with the same problem. The only advice I can give, is that..... If your back is hurting, you think it may be from phen, and you bowl, don't bowl until your back doesn't hurt anymore!

I made this mistake and went from feeling better, to worse than I was initially.