Meds for MRSA or the Plain Old Stomach Flu?

Well, we started on meds for the MRSA condition for the littlest one, the middle one started complaining of a headache and the oldest one said that she jammed her finger. Well actually what she said was that she was sure her pinky finger was "splintered".

Then about 10:30 last night the little one who was getting in a little sympathy co-sleeping time woke up throwing up. It was very strange in that I became aware that she was wiggling through the fog of my sleepy exhaustion, but assumed that she would settle back into sleep. To make a long story short, she did not. She began to vomit up what she had eaten for LUNCH ten hours earlier! I know this is gross and disgusting, but what would cause food (chickpeas to be exact) to just sit in her tummy, undigested for that long a period of time? Would it be caused by the antibiotics they are giving her?