How Can Neck Region Pain Be Treated With No Adverse Side Effects?

I have been taking Hifenac P every 2-3 days for the last one year due to severe pain in the neck region.There appears to be no cure at this age( I am 83)No other pain killer is useful. Please tell me about the side effects I am willing to suffer the agony of pain rather than losing my kidney or liver. Thanks Nervous patient.