Many people also get drowsy as they receive treatment, which is why we offer private rooms where you can relax and rest
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
And products with food dyes, like candy, gelatin, and certain breakfast cereals, might turn your urine green or blue
Mol Nutr Food Res 2015;59:1364-1372
b) the widespread use of antibiotics in animal farming, which impairs B12 production by the animal gut microbiota
What Is Vitamin B12 Injection Used For