Hi There I Am Very Worried About My Son He

Hi there I am very worried about my son he has pain in his shoulder, neck collarbone, lower back hip, foot and is now saying swallowing is uneasy. He had food poisoning about 8 weeks ago and then got a very sore neck and now it's developing in so many other places. He is under a doctor but they don't know what it is, he has had blood tests x Ray's and ultrasound. Please do you have any suggestions?