B12 injections and Bladder Irritation

[UnitNitrogen73]

Hi, ...I have just started self injecting b12 once a week. Interestingly, the day after each injection I experience bladder irritation as you would get with cystitis but the burning pain subsides before the next injection. The GP has given me an antibiotic as says there is now an infection but the tablets don’t seem to be helping. It just seems too much of a coincidence and wondered if anyone else has experienced b12 injections having this effect. Normally I am not susceptible to cystitis so this is somewhat a mystery. Any thoughts would be appreciated. Many thanks