From a practical perspective, if the tremor resolves with medication interruption this would link the side effect. If the tremor returned with rechallenge, that would be convincing. Otherwise, it would be hard to know if the tremor is related to antiretroviral medication.
What I can say from my personal experience is that tremor related to antiretroviral medication is extremely rare. Since you have switched him to an alternative regimen perhaps you can provide some feedback and let us know if the tremor improved.
With regard to the new regimen, it may work, but triple nucleoside regimens are not as potent as NNRTI-based therapy. It is likely that Viread (tenofovir) will make adefovir unnecessary since it has very similar activity against hepatitis B. HBV serology may be helpful, but a quantitative hepatitis B DNA done on Epivir prior to the switch would be the baseline test that I would choose. Then you can see what happens to the HBV viral load after the switch to tenofovir.
