What Causes Severe Abdominal Pain Which Spreads Throughout The Body In Child?

Logan is 8 years old im his dad. He began having pain on and around his bones about 3 weeks ago (feb 1 17 ) . It seems to start after eating and is worse at night. About 5 minutes after eating pain starts at the belly button and quickly moves to the ribs and throat. He felt like he was gagging/tightness in throat. Dr thought this to be excess acid so started zantac but hasn t worked (7 days in). Here is the strange part. About 10 minutes after stomach pain at ribs and tighness/gagging in throat, he begins experiencing body pains. First his hip begins to hurt (at the top and he says it is the bone itself, not the joint. The pain then travels all over his body, mostly around bones. It hurts around his shin bone (all up and down the side where it attaches to connective tissue. It hurts on tops of his feet on top of the bones. His hands begin to hurt (not the wrist but hand itself). Feels like someone is pinching his arm tightly sometimes. Spine at base of his head also (says it mostly hurts on the bone and a little on the side) and tailbone. 2:54 PM 2/22/2017 No fever. CBC and ESR CRP all normal. stomach x ray normal. The pain last for hours once started, tylenol motrin little help. The pain lasts a few minutes in each area before moving on, moderate intesity. Does not seem joint related at all and he says mostly hurts on the bones themselves esecially the tail bone, ribs (he says ribs themselves when i press on them and not underneath), and back of skull (middle but moves to the top and forhead). Dr has never heard of stomach pain starting in upper stomach and spreading like this to the rest of the body. Any ideas would be great help, nights are no fun, very concerned.