I'm thinking based on this you may be allergic to opium, which is
why the true synthetics work best for you.
, hydrocodone are all semi-synthetic derivatives of opium.
True synthetics are fentanyl, sufentanil, alfentanil, and methadone. Methadone is converted to hydromorphone in the liver.
Dilaudid is hydromorphone, so that may be a good one for you.
Hope this helps.