Oxycodone 10mg Immediate Release Question?

My doctor had me on Percocet for a long time until at the end of this past March taking three 10/325 pills at once wasn't helping my pain at all. At the beginning of this month he moved me to just plain oxycodone HCL 10mg tablets. Taking 3 and a half pills at once gives me no relief. I've even taken 4 pills at once and have gotten no relief at all. I'm afraid to take more than 4 pills at once because suffocating is my worst fear. People say I shouldn't have any problem taking more because of my tolerance but I'm extremely scared but the pain is so bad that I need relief even if it's just a little bit. What would be ok for me to take without causing myself to die. I want to find obviously the minimum amount needed to take for pain relief and just this morning 35mg at once didn't give me any relief or even make me tired at all. I have very bad anxiety too which is why I'm trying to find out what is safe for me to try based on the tolerance I personally have to this drug. Can anyone give me an idea of this so I won't have to be scared and go into a panic attack just trying to get relief?