Sick Dog????????????? Help?

I took my dog to the beach today and she was all good until she started to drink the salt-water. She normally does this when I take her to the beach. I take her like twice a week to the beach. But today she just started to throw up from it and had diarrhea. So i immediately washed her in clean fresh water. She drunk the same amount of saltwater she would normally. I have recently changer her food. Is this the cause of it> She eat like half a hour before i took her out. Should i be worried?