From your description, it appears that the pain started after receiving 3 epidural injections. If thats the case, nerves may have been damaged during the procedure and he may be experiencing neuropathic pain. Additionally, the bacterial infection leading to the cardiomyopathy may have also damage some nerves.
The best initial step in the workup of your husband’s pain is to identify the source. There are pain killers and procedures such as nerve blocks that can be employed for unrelenting pain. If he has not done so, your husband should be worked up by a pain specialist – some neurologists and anesthesiologists train in pain management and are experts in the field of neuropathic pain management.