Pelvic pain on left side

Please clarify your question

Well that narrows it down to a number of things. Muscle strain or pinched nerve would be a start, There are no organs, per se, on that side so appendicitis is probably out. When-all day? exactly where, standing, laying down, sitting? Constipation? Diverticulitis is usually higher but who knows. Seen a doctor yet? Any tests? If not, why not?

Wow, that's not a lot of info to go by, so my advice, see your doctor. Hopefully you'll give him/her more info so they can find out what's going on.