Bless your heart! I understand that it is made from ceramics. You should talk to your doctor about the different options available as there is more than one.
I too am allergic to nickel and after two years of testing I now have the Oxynium knee in. Although it does contain a trace amount of titanium ( which is where the nickel resides) the amount is minimal. It has only been three weeks for me and so far I am not sure I made the right decision.
Is your Oxynium replacement still doing well?