Thank you for your question.
I am Dr. Su S. and I will try my best to help you.
When did the diarrhea start?
How many doses of benadryl did you give?
When did all the symptoms develop?
How old is he?
Diarrhea started yesterday (tuesday 10-1), he has benadryl Friday, Sat, Sun. 1 dose a day ( I usually give half of the suggested dose)
His runny nose and cough started on thursday 9/26