I don't know whether the colour of your stool is caused by the medications. However, if your stools are black/tarry then this indicates intestinal bleeding. The medical name for stools of this nature is MELENA. You could try typing it into google/yahoo etc and studying one of the listings.
Anyway, bleeding and/or melena is never normal and should be investigated promptly.
Good luck
Morecambe
i forgot to ask, could the black stool be from the advil i was taking? also, while i was taking the advil, i wasn't eating very much.