I have been taking tramadol for about 1.5 years and have not noticed any tolerance to it. I reduced my dosage from 200 mg per day to 150 mg at some point. It is possible that your condition is just getting worse and that is why something doesn't work as well as it used to. I have been taking gabapentin for about 10 years and haven't developed a tolerance to that either. Some people claim they have.

FYI--I have been taking biotin, 5 mg per day, for a couple of months now and it appears to have reduced my pain, so you might try that. Biotin has shown in studies to reduce pain in patients with kidney-failure-induced neuropathy.

Also alpha-lipoic acid (Jarrow sustain with biotin, 600 mg per day) and evening primrose oil (TwinLab Mega primrose oil, 2600 mg per day) reduce my pain.
Ron