I Currently Have To Take Oxycodone For Constant Aching In

I currently have to take oxycodone for constant aching in my muscles. It's the only thing I have found that helps me. My doctor says it's okay as I only take a 20mg tablet and I cut that in half. I have recently found out that tizanidine helps with muscle aches. Can I take the tizanidine also. These tablets are only 2mg.