Vitamin B6 has been linked to nerve damage, but usually at much higher doses (like 300-500mg/day, for 6 months or longer). So the dizzy spills could be caused by 100 mg/day, but unlikely. Usually you would have other nerve funniness first, like tingling in the wrists.
I have taken B6 for morning sickness and Carpal tunnel, which is why I've researched it. Most sources would say that 100 mg is entirely safe.