Hi RoseKibit,
I'm sorry to hear about your son's headache and finger "lock up" problems. I can't comment on the headache, but muscle cramping, like with the finger lock up, is a known side effect of Revlimid.
Awhile back there was a Forum thread about muscle cramps, with lots of people suggesting remedies that have helped them:
"Muscle Cramps" (started March 12, 2012)In my case, with mild cramping, mustard sometimes helps. With more severe cramping, drinking about a half cup of water and vinegar in equal portions works to unlock things. My myeloma specialist has also had me add magnesium oxide as a supplement, and that seems to have reduced the frequency of cramping incidences. Also, staying hydrated helps too.
Best wishes to your son. I hope his treatments are helping him despite these side effects.
Mike