I've had a popping and snapping sound in my right shoulder for years. Was told it was inflamation of tendons and muscle. Use Icey/Hot gel found at local Pharmacist and ice. Heating pad before bed if available. Seems to work out the kinks. Used to work for a local grocery store warehouse, so the heavy box lifting all day combined with archery practice/hunting and any other activities that may come around tend to irritate the shoulder areas. But like I said the icey/hot gel, heat and ice seem to work for me along with a few days of easing the use of the shoulder as much as possible.