I got struck in the forehead by a door at work earlier pretty hard and saw stars, although i didn't black out. it's been about 12 hours and i'm slightly dizzy with vision that shifts between blurred and focused, but i'm also running on very low sleep?

Keep it simple between your head concussion and being sleep deprived. Rest will help both and symptoms should improve, however if persistent dizziness or vision changes getting a medical evaluation should help in clarifying as other conditions not even related to mentioned events cannot be ruled out.

Mild closed head injuries are ubiquitous and usually require no medical attention. If symptoms worsen, such as increasing headache, dizziness and/or loss of balance, nausea and/or vomiting, progressive visual blurring or double vision, weakness, or episodic loss of awareness; time to seek medical attention.