sorry you're on b-2? or b-12? it really depends if your weakness is caused by low b12. there are a few different things that can cause weak muscles.
my very first megadosing protocol was a modified, oral-only version of klenner:http://www.townsendletter.com/Klenner/klenner4.htm
mostly i just found 100mg pills for all the different b vitamins, plus i took vit c, vit e, and lecithin, and i think that was about it really.
i didn't do the minerals at the time, because i was overloaded with new info. but i would not omit them now. also klenner is missing vitamin d3 in his list of recommendations (the research hadn't been done yet when he wrote it up). also, i would not take the vit e he recommends now. only natural ratio vit E8-complex with 4 tocopherols and 4 tocotrienols.
i guess neuros are not trained to treat with nutrients, luckily the interweb will save us all