3 Yr Old Grandson Woke Up During Night Crying For

3 yr old grandson woke up during night crying for water but when mom gave to him he couldn't swallow it. Also refused to drink anything else. He went back to sleep & woke this morning with badly swollen face and a rash all over his body. No one else had these symptoms in the house. He had a fever last night, but seems to feel fine today except the swollen face & rash. Should mom take to the ER?