This is bizarre. It's been less than a month since diagnosis of B12 deficiency: level 68. Started on cyanocobalamn 1000/day. Some amazing improvements within two weeks, some almost immediately: mouth sores gone, tongue no longer burning and red, lips not cracked. Feeling started to return to fingers to name a few. After several suggestions here and my own investigation, switched to Methylcobalamin (Jarrow formula). Increased dosage to 2000 daily. Since then, approx 10 days ago, my symptoms are returning. Leg numbness worsening, especially knees and feet; fingers buzzing more; l'hermitte as bad as ever. And finally, after being able to type easily for about a week I am now having trouble again. Please help with any possible input. Could this have happened with either type? Did my switch cause this? Methy is definitely the preferred especially with so many neuro symptoms. I've babbled enough. Just thought someone might know something. My plan is to go buy some cyan B12 at Xmart early tomorrow morning and stop methyl. Bloodwork is scheduled in less than a week. I'm distressed, discouraged and CONFUSED. help. Nancy