Fatigue is common following a stroke or brain injury. It can be the most common complaint in people with disabilities because everything from thinking to physical activities can be more difficult. There is probably also an "unknown factor" that leads to this feeling of no energy.
Your husband is functioing at a high level following his stroke and is missing his "old self." He is beyond the usual suggestions of rest, pacing and energy conservation. If you went to a health food store they would suggest a variety of supplements and vitamins to improve his energy. I am not a big fan of these, particularly in your husband's case. Many of the supplements can affect blood clotting and lining of blood vessels. For instance, Gingko biloba can cause excessive bleeding.
There are a number of medications that we use to improve fatigue in disability. Many have been tried in multiple sclerosis, brain injury, stroke and spinal cord injury patients. They all fall into the category of stimulants and can be safely administered to the right patients under the supervsion of a physician. I am not sure if your husband would be a candidate since they can make high blood pressure worse and this would need to be closely monitored. The use of all of these medications is what is called "off label" and you will need to find a physician who is comfortable working with your husband. Off Label means the drug company cannot promote their use in certain unapproved areas, but many physicians and patients will use the medication for things they know from experience are helpful.
If you primary care physician is not comfortable treating fatigue, then ask for a referral to a rehabilitation physician who cares for stroke and brain injury patients. Some rehabilitation physicians specialize in sports medicine, back or neck pain. This type of physician may sound like what your husband needs, but he needs one who deals with stroke patients all of the time.
Don't forget to remind all his doctors about his high blood pressure and clotting disorder. Trust the judgement of those who know his condition. They can also determine if there are other medical reasons to account for his fatigue.
Good Luck.
After your stroke you may be experiencing a new normal, but remember what George Eliot said- It is never too late to be what you might have been. You still can achieve new goals.