It may just be normal muscle twitches, or anxiety.

The onset of deficiency tends to be insidious but symptoms include loss of energy, agitation, muscle twitches, restless legs in bed, tremor (the shakes) and nausea and vomiting.

Then, a few years later, aged 33, he started to notice that he was getting muscle twitches and spasms in his back.

Every muscle twitches to keep balance.