I don't really doubt him and I'm not a Tiger fan either. I'm also 38 and I've had back problems creep up the last couple of years while playing golf. They don't go away, the best you can do is cope with them and hope things don't go sideways on you during a round.
If my back is bad, I have the luxury of skipping playing for a while, even if I don't want to. Being his livelihood and the demands of sponsors, etc., he doesn't get that benefit for the most part. I would prefer if I had his money though. Would make things easier when the back is bothering me.