My friends brother in CA. ate beef at a resturant the other night. He's been sick ever since. And can't stop having diareahha. I think He has food poisening, E coli

Trudy,
Thise are signs of Food Poisoning. He needs to go to a Doctor. It could have been the Beef, but it could have been something else.
The reason I say this, is many times, healthy people are able to stave it off and it never gets reported until someone of immune compromised condition (Very old, Very Young, Cancer Patient) is hospitalized.
Your Friends Brothers illness could be from something as simple as cross contamination or poor restaraunt cleaning and Hygiene practices. Or, it could be a batch of bad meat. It won't be known until local Food Safety inspectors get involved. And even then, it may take looking at several cases to determine,
Pat