Nomad2

I have arthritis in my hips, mostly in one side. Have been riding my touring bike with no pain at all for a while but had occasion to ride my mountain bike last weekend and the pain was back! I really felt there was something slightly out in the bike setup and that my left leg felt further out than my right when pedalling (the left is where the problem is for what it's worth). When I got home I measured the distance from the bike frame to the centreline of the pedal on both sides and indeed found that the left side was 5mm further out than the right. It is a 17 year old mountain bike with non-original crankset which is about 10 years old. Could this small difference be enough to contribute to my hip pain? Is it worth correcting? Should I do this by getting the cranks looked at (if something can be done there) or compensating with the shoe cleats?

Thanks in advance

Alan