Wow ~ Well I have heard of people herniating a disc by coughing. I have actually broken a rib by coughing! Now, that's really COUGHING!
It doesn't sound like fibro pain to me, but I'm no "expert" on it either.

I would think that you should have an MRI of at least your lower back, and make sure they do it with and without contrast material.
Let us know what happens, ok? I hope you're ok. God bless and please take care. Hugs, Lee