I Have Been On Oxy 15 Mg Three Times A

I have been on oxy 15 mg three times a day my Dr cut it down to 3 times because I also take Ativan. My Knee started giving trouble 3 weeks ago. I have had 2 torodol 60mg shots, my question is I am out of pain meds. The dr put me om 800mg of motrin and because I have chrohns It really made me sicknausea and vomiting. Will I go into withdrawal I can get then on the nineth??l