Is A Big Bump With Red Spots On Head And Nausea Post A Fall A Cause For Concern?

My cousin fell down the stairs and hit her head last night. She now has a big bump and there are red spots on the bump. She says she has a minor headache and her head is very sore. She occasionally feels like puking. We think she has a concussion. What do we do? Should we take her to the ER or should we let her sleep?