Has anyone else experienced these symptoms or have a recommendation of medical path?

[DragonflyLady]

My 19-year-old son got sick in October 2015 with flu-like symptoms and a molluscum looking rash. He had severe diarrhea, fatigue, generalized weakness, severe lower abdominal pain, headaches and brain fog. Over this time, the flu-like symptoms and diarrhea subsided but the rest of the symptoms have remained. The rash comes and goes. The last month, he has developed severe chest pain. Today, he couldn't lift his right arm and had tingling in chest and both arms.
We have been to multiple doctors and specialists and many trips to the ER. His CBC is normal. It isn't his appendix or his gall bladder. He's had a colonoscopy and endoscopy. He had some ulcers in his throat but that has been treated. They've looked at Epstein-Barr, C-diff, Rocky Mountain Spotted Fever, Lyme's Disease, and giardia. They've done a head CT-scan. They done an EKG, chest x-ray. All unremarkable.
Three doctors referred him to an infectious disease specialist but the doctor refused to see him after looking at my son's records. We've seen an endocrinologist and, of course, the GI doctor.
The pain through his chest is so incredibly severe that he can't sleep, go to school or work. He got a little better in August - September of 2016, but it all started up again in October 2016 (and now has the added chest pain).
The pain was so incredibly bad today that we put him on oxygen. It helped with the pain, tingling and he can move his arm. His oxygen level has always been fine. We have no idea why it helped.