My 18 Month Old Hit His Gum Really Hard Today

My 18 month old hit his gum really hard today i looked in his mouth and it looks like one of his tooths moved back. It has been 8 hours since it happened. I put him to bed, went in to check on him and saw his bed sheet there was circles of saliva/ blood on it. Should i take him to the er? Dont really know what to do.