left side pain

I have been having very sharp pains on my left side for a few days. It seems to be quite unbearable when I breathe in deeply. I've also experienced something similar in my left side lung area. I've been to the doctor and he tells me the chest pain was from inflamation (inflammation) of my joints in my rib. he prescribed anti inflamitories that never really helped and told me I need more rest.  now that it has moved lower into my abdomen I'm starting to worry. there are no joints there to be inflamed. it is much more than gas pains. I hate to waste any more time or money to go to the ER if there is no explination.  I'm hurting severely and I need releif. Is this something I should worry about? should I go to the ER or is there someone else I should see specifically? please help if you can.