Question
my chiro does decompression on my lower back with his hands pulling down my pants and underware and raising my shirt just a bit It makes me a little uncomfortable is this normal?

Answer
thats called flexion distraction. as long as he is professional about it i wouldn't worry. if he press' down towards your feet its correct. he may need to feel the spine , but he should not pull your pants down below your tailbone or past the crack of your butt.
if you have sciatica is he releasing your psoas muscle in the front of your pelvis?