I hit my head very hard last night, got 5 stitches. Now im very tired and feeling dizzy/confused having trouble concentrating. Should I go back?

Yes! Definitely go and get checked out. You may have a concussion based off of your symptoms.
Concussion. You are exhibiting typical symptoms of a concussion. You should do things that reduce your brain activity, such as not watching tv or playing on the phone or computer. Giving your brain time to rest is what heals a concussion and you should follow regularly with your physician for resolution of the symptoms.