It takes your body a while to settle down after a radical change in your diet. I don't eat wheat (i'm not a ceoliac) so i'm not GF but I noticed a real change when I gave up the wheat because i used to have constp..
Codiene and wheat can give you const.
If you have joint pains another thing you can do is go on the Hay Way Of eating which is not mixing carbs and protein. Also only eating fruit when you're truly hungry (on an empty stomach) I don't have any joint pains now I do that.