Seems to Crave Charcoal or Wood

Our rescue JRT seems to be in good health, but seems to suffer with some sort of tummy ache? When we had the wood burner lit, she would clear up bits or charcoal that fell out and/or chew some of the logs - especially after meals. She is wormed reguaraly and has a good unfussy appetite with no apparent allergies. I occasionally give her a bit of natural yogurt which she loves, but it seems to make no difference.

I cannot just buy charcoal biscuits locally although she seems to like the ones in Shapes, but there are only a few per pack and do they have much charcoal in them? Is it worth buying the specialist charcoal from an ebay outlet, the only place I have seen it, or does anyone know of an alternative?

Or even why she is doing this?

What do you feed her on?

We have tried several different options. However, since OH has stopped tidbiting with custard creams and crisps the craving has stopped.

So I think I have found the answer! They are currently on a dry complete mid range priced feed and now no tidbits, no tinned feed, just occasional bit of chicken, egg or pasta.