pelvic misalignment-sciatica

i'm going out on a limb here - pardon the pun ....

but from playing snooker every night of the week for 4 months, which involves placing your spine and pelvis in a very unnatural position then to suddenly quit playing snooker because it has caused an an RSI ...is it possible that i've put my pelvis out of alignment causing my piriformis to tighten up ...

as a result this has caused the sciatic nerve to tense up... now when i stand up for a few minutes i get a gradual onset of cramp in my hamstring ......when i sit down for a minute the pain subsides as if i wasn't there ....

i went to a new physio on monday ...he suggested nerve gliding very gently to begin with ?

i have no pain in my bacfk at all .... i am convinced that the root of the problem is to do with my pelvis and piriformis ...it is causing me to walk funny too

please help