I expect you did the change to applaws gradually, but if not that could have caused a problem with his tum. Was it a marrow bone you gave him? Sometimes the marrow can be too rich until they are used to it, WIth Beamish's first marrow bone I scooped a lot of the marrow out first, and even now I limit them to an hour with a marrow bone, then double wrap it and put it in the fridge. They can have it as long as they like on the next day.
Wind is often generated by food high in carbs - meat is digested in the small intestine by enzymes, but carbs are processed in the large intstine more by bacterial action than anything else - more a fermentation than a digestion, and that can generate gas, but any digestive upset can lead to food being passed throug hto the large intesting only partially digested.
Sometimes giving a pro-biotic supplement such as this http://www.thefulvicacidcompany.com/ful ... nswer.html
can get the digestion back on track - it's good when introducing new foods too.
Poor Murphy - I hope his tum gets sorted soon.