I have upper abdominal pain and am throwing up. have a past diagnosis of acute pancreatitis. go to er or a stomach bug? how long do i wait?

Depends: If you had the type of pancreatitis that landed you in the hospital for several days, that would indicate that you had severe pancreatitis, hence i would not wait very long. If it was managed as an outpatient, then it was less likely to be severe and you might be able to wait longer> this is not an easy one to answer without more info, calling you primary md sooner rather than later is wise.