I agree with princess...I'd totally give up the coke and any soft drink for that matter, as well as the ice cream...dairy can cause the issues you describe and so can carbonated drinks, and at your age (not saying you're old, heck, I'll be 41 this yr) but carbinated drinks do a number on the old bones well before their time, it's hard on the gut and not to mention all the sugar that is packed into both the coke and ice cream.
Just my 2 cents :)
And it's good that you at least do alot of walking, that's better than nothing at all.
My bum is broken....there's a big crack down the middle of it! LOL :)