Until i can get to the doctor for my pelvic pain, what's the most effective dose and frequency for ibuprofen? when i take 800mg every 8 hours, it seems to wear off after 5 hours or so.

You are at max: recommended dose of ibuprofen, you could alternate tylenol 500 - 600 mg 3 times a day, between doses of ibuprofen, if no allergies, never exceed max doses of either medication. Gastric bleeding with ibuprofen, liver failure with excessive tylenol.

800mg every 6h: You can technically take a maximum dose of 800mg every six hours of Ibuprofen. BUT, I wouldn’t do this for more than a couple of days in a row. Certainly wouldn’t take this dose every day for a long time. If this dose doesn’t help, you would want to entertain another analgesic or consider reviewing the pelvic pain diagnosis.