I believe i was harrassed by probation officer?

i was given a urine test,have done many,however, the last time i feel i was harrassed,its hard enough to pee.i started peeing he was behind me then swiftly as i started ran up on me,not letting me finish and took the sample,i was attacked from behind years ago and haveing flash backs should i tell my po first or go to the supervisor,i dont feel this was rite,or just file a complaint?