Hi!
I had gone through your query and understand your concern.
In my opinion you don't need to worry because
diarrhea and spitting are not symptoms of
head injury.
First at all the height is not large enough to cause a serious damage to the head of your baby and second thing if your baby has had
head trauma In the first 24 h you had noticed symptoms such as crying,
vomiting, after some time somnolence,lethargy up to coma.
If your baby is normal (no vomitig,sleeping normal,reacting normal and eating normal) you don't need to worry.
The presence of diarrhea makes me think he has an viral infection of his digestive tract(gastoenteritis ).
You just need to be careful to treat
dehydration if his diarrhea continue.
Give him to drink plenty of fluids.
Hope it answered to your inquiry!
Wishing good health to your baby.
Take care.
Dr.Rovena