The throat constriction could be caused in part from the drugs. However, from what you have posted it sounds stress related...meaning he does fine for a while and then it starts in again.
I was in an automobile accident that did everything but wipe me off the face of the earth. I reached a point where I could not eat anything without vomiting. This was stress related. His digestive track will never heal if he is still taking drugs. And a chiropractor did not help me.
I also had to go back to work while I was extremely ill or risk losing a job I needed.
May I ask what his injuries are? Were all the digestive problems before the accident? If so, were they made worse by the accident?
Are you using any type of oxygen therapy? Do you have access to an infrared sauna? Is he taking mineral supplementation. Does he know about EFT? This will help him deal with his stress. Is he able to drink ACV? He needs dense nutrition.