Is there a Dr. in the house?

We have a sick ward around here these days.  My oldest daughter has been sick for the last 14 days.  It is the strangest sickness I have ever seen and if I didn't know any better, I would think she is faking it to get out of something.  She seems fine throughout the day and at night, she spews everywhere.  There is nothing worse than waking up in the middle of the night and needing to clean up vomit.  She really wants to go back to school and we have gone to the Dr. two times already.  It seems as though she has ingested a parasite of some kind and it is trying to work itself out.  Apparently, it one of those bugs that just latches on to the insides and refuses to let go.  I feel so bad for her and all I can do is hold her hair back and encourage her to "get it out".  All I can say is when that parasite gets itself out of her body, I will stomp on it to make sure it is in fact dead.