Hi, thanks for using healthcare magic Though head trauma can sometimes cause vomiting, it is not usually associated with diarrhea. The fact that she has both implies that it is not related to the head trauma but likely due to an infection of the gastrointestinal tract. Most infections are viral but bacterial infections can also occur. The main aspect of treatment of vomiting and diarrhea involves preventing or treating dehydration. Dry skin, decreased tears on crying, decreased urination, increased heart rate, drowsiness and dizziness can all indicate that there may be dehydration so you would need to monitor for these. If present, she should be seen by her doctor Treatment: (1) no solid food till a 4 hour window with no symptoms then restart small amounts of solid food (2)oral rehydration fluids such as pedialyte. Initially small amounts frequently, if tolerated, the amount can be increased eg 1 tsp to 1 tbs every 5 mins for an hour, if tolerated increase (3)probiotics may also help as well. These can be used on their own or in yogurts I hope this helps