You have a acute diarrhea
which leads to dehydration
as lot of fluids and electrolytes are lost from body and can cause a person to faint and low BP
and hypovolumic shock
I hope in case of emergency you already musthave been taken care.
Yiu should take rehydration fluid (ORS Oral rehydration fluid) many commercial readymade drinks are available and if you have to much vomiting
then simple antiemetic may be of use.
If dehydration is severe and BP is low Intravenous fluid need to be given in the hospital.
If you are OK and no vomiting fluid and fruit juices can be taken to keep you hydrated and may be self limiting illness.
Good luck to you