I am 18 and i think i have severe memory problems. what doctor should i talk to?

Neurologist: Typically you should see your medical doctor first and if there is a significant problem they will refer you to a specialist (neurologist).

A few questions: Is this new or has it been happening for a while? Was onset sudden or gradual? What is your definition of "severe?" have you lost memory for well learned info or just new info? Is your memory loss for facts, dates, procedures or word meanings? Do you forget where you put your keys and find them in the refrigerator? If no recent accidents or med probs, you may want to see a neuropsychologist.