I was dx w/ addisons. im on hydrocortisone 1 1/2 am/1 pm 10mg. today i been lightheaded all day, lethargic, and now vomit brown liquid. go to er?

Addisons: Yes would go to the ER IMMEDIATELY. Did you eat something brown ( like lots of chocolate) ? or does it look like coffee ground? if so it could be a ulcer / Gi bleeds as cortisone can irritate the stomach, so you must go to the ER. Also at a time of physiologic stress you need more cortisone which you can not produce so that would cause lower BP lightheadedness- as may bleeding . GO TO ER NOW