It would be a really good idea to get a 24hr cortisol saliva test that includes sex hormones. It is entirely possible that you weaned off too quickly, too soon. Your symptoms may have been not from too much cortisone but not enough. Cortisol is supposed to rouse you in the morning not cause excess sleepiness. The saliva test will help you figure out what is causing your problems.
Abruptly stopping anti-depressants can cause problems too. What was the anti-depressant you were taking? A fluoride based one (like prozac) needs to be weaned off slowly from.