First off, good for you cutting back as much a you have, that's a huge improvement.
I want to make note here. I'm not a doctor. This is why anytime someone asks advice for anything physiological, the first responses are to go see one. Even if I were a doctor, it would be illegal and unethical for me to practice over the Internet. I'll try to help you as best I can, but what I don't know about medicine could fill a warehouse.
How long have you been able to go before starting them again? From what I have been able to research, it can take upwards of a month for the withdrawals to pass.
Have you always been on Effexor when trying to quit the Gravol?
Effexor can make you feel pretty shit as it is. It wouldn't surprise me if it would make something like that worse. (If course, I'm not saying you should quit your meds. No, no, no, no.)
Does your doctor know the extent of how much you were taking and for how long?
If not, then you absolutely need to inform them. You will not get in trouble, nor will you be forced into psychiatric care. Especially since you have lowered your dosage as much as you have. You simply don't qualify for sanction under the Canadian mental health act.
Also since you have baseline of stability to fall back on, your doctor can work with you to trial and error some methods of getting you the rest of the way off of the gravol.
Have you had bloodwork done?
Drugs like gravol block receptors in the brain from absorbing certain transmitters. This can result in deficiencies that need to be dealt with in order to help you feel better.
Also remember that this kind of addiction is somewhat unheard of, there isn't a lot alot of literature on how to treat this. If you find that the doctor you're seeing isn't giving you useful help, seek a second opinion.
Also look into a different rehab program, they are not all the same, if the one you went to already wasn't helpful, don't give up. There are tons of different programs, it's likely you will find one that is helpful for you.