What Could This Be? (Pregnant?)

Ok so I went to the ER with vomiting about 10 days ago and couldn't take my pill for 3 days. It was one week after I finished a period. When I could take the pill again I just picked up where I left off and took 2 one of the days to try and make up for missing them (I know, not supposed to do this). Now I've been on my period for 9 days, light flow for the most part. (To summarize - I was only off my period for 10 days before starting another one and I've been bleeding for 9 days now). I called my gynecologist to ask if it was normal to bleed this long when you miss pills. She said the dr. would like to see me in the morning just to "make sure it's not something else". What is the "something else" it could be? Do they think I might be pregnant or are they just being overly cautious?