Gluten-free old biddyness

I went in for my annual physical the other day.  Because my former physician has moved on, I have a new one.  She is a 60-something, slightly crunchy granola/stereotypical Ithacan.  Anyway, I mentioned that my knees have been achy for no apparent reason.*  She instantly suggested I try going gluten free for a few months.  
I'm dubious, but will try it. I know that I felt pretty good when I was rigorously following a low glycemic, Zone-type diet, which is fairly low gluten.  Although I'm not rigorously following the Zone nowadays, I've kept some of the habits I developed, so  I don't eat a whole ton of gluten - maybe equivalent to two slices of bread per day or less.  Nonetheless, I do like baked goods.  This is going to be tough - not as tough as giving up dairy would be, but still tough.
I'll give it a shot for three months, as suggested.  I'm not going to get my panties in a bunch about homeopathic levels of gluten, but will cut out wheat/barley and see what happens.  Sometimes all the dietary advice I get contradicts itself.  Soy and cruciferous veggies are good, except if you have a thyroid condition and then they're bad.  Low fat or low carb?  Is coffee good or bad?  Is dairy good or bad?  What about artificial sweeteners?  Inquiring minds want to know.  It's frustrating.  I'm normally a fan of moderation and common sense, so this is something different for me.

* Some other causes might include my knees getting tweaked from the appx 30 flights of stairs I climb every day, or the two cats who sleep on my legs every night, me wearing unsupportive snow boot too much, or my thyroid med prescription being too low.