I'm on the medication lithium but I haven't taken it for about 4 days now I'm starting to get very light headed and dizzy when I walkorstand?

Get help. You're likely having symptoms from abruptly stopping lithium. Should not be stopped without medical supervision for this reason and to monitor your mental status. Please call prescribing doctor immediately for advice. Tell a family member or friend what happened and ask them to help you walk b/o dizziness. Have someone by your side for safety reasons to see your doc or go to urgent care for eval.
Lithium. Please talk to your doctor right away or go to nearest ER. Abrupt stop of these meds can cause extremely severe anxiety or wild mood change. Please don't wait for a routine appointment, this really is urgent. Also talk more with your prescribing doctor to get more help on why you need to carefully follow their prescription. Please seek help in person today.