Your husband is blessed to have you as his champion!!
Yes, most doctors are big pharma trained drug pushers who are more interested in fleecing the patient than in getting them well ... that means lots of tests, scans, probes, referrals, x-rays, and lots of DRUGS. When they say they are PRACTICING medicine they aren't kidding. They have a $$$$$$ agenda. There is NO money to be made in getting people healthy, only in keeping them sick, even if the patient DIES in the process. Doctors aren't God and they have NO RIGHT to proclaim death to a person!!
Ok, please forgive for the rant, back to your situation.
I hope and pray you can speedily find someone [in addition to HV and other educated, caring folks here!] who will find out what is truly wrong with your husband and show you the way to treat and cure him, whatever it is. Just like on the TV Show, Mystery Diagnosis, you might have to go through a LOT of doctors before you find a good one who will listen to you and truly offer the caring and compassion to get him well. Don't give up and don't let hubby give up!
I am praying for you both that your path will be made clear and that health and healing is close at hand!