4yr old started constantly crying for little things like asking her to go potty, doesn't know where something is, etc..what could be the sudden change?

Childhood anxiety: These symptoms sound very suspicious for acute onset of some type of anxiety. Small children generally show their anxiety through whining and crying as you describe, not the typical ways adults experience anxiety. Has anything you can think of been altered in her life over past months - from a move to change in care, to where she sleeps, death or illness in family member. Would suggest child psych.