Are Livogen, Fol5, And Renerve Injections Causing Side Effects Of Black Stools, Weakness, And Body Pain?

Hi..i av deficiency of VB12....not more even though doctor adviced to take livogen n fol5.Weekly twice Renerve injection...i av tonsils ,ulcer,and running nose.Weakness n body pains...Nw I av seen that my stool is in black colour...soo i want to know whether the tablets are working or not