I'm forgetting how to spell the simplest words. what could cause this memory problem?

Neuropsychological: Evaluation might prevent unnecessary & unhelpful worry. I can imagine how frightened you may feel. Anxiety can make symptoms worse so, if you can, have a good eval. Results might guide important decisions that can nip a problem in the bud or rule out things that you fear. As young as you are, this may be a good time to prevent or slow down any early disease progress that there is. Good luck!