Motor : muscle weakness, ataxia, reduced reflexes (if peripheral neuropathy) or increased reflexes and/or upgoing plantars (if central neuropathy)
Lederle FA, Johnson DC, Wilson JT, et al
Always good to have a reason I have also had this happen when my folate was low , it may be worth you getting it checked I had self inject my B12 every 4 weeks for the last 20+ (cannot really remember how long accurately), and 2 months ago got a similar 'electric shock tingling' all over my body - head, face, arms, hands, legs, feet etc within a couple of minutes of injecting, which lasted about 3 seconds or so
Beyond 28 days, oxidative degradation and aggregation increase measurably
IV therapy takes a different approach by delivering B12 and other nutrients directly into your bloodstream through an intravenous drip
Anemia can cause weakness and fatigue