We started out using Enfamil Gentle-ease and switched to SS after a month and a half. My daughter also had painful gas and the doctor thought she had colic. SS seemed to help, but we also used Little Tummys Gas Drops so it's hard to tell which one helped her more. She is 3.5 months old now, still on SS & gas drops as needed, and gas pain seems to be minimal for the most part-though still loud and stinky!! ;)
Have you looked into gas drops or gripe water?