I have been sick for 1 1/2 yrs now. Extreme fatigue, nervous, shakey, chills. Down and out and unable to work or get off the couch. Been on xanax to try to calm things down. Monday I got my 1st b12 shot. Today I was NORMAL. My allergies were gone, as was my nervousness. I had energy. It was like the past year was just a bad dream. My Dr said to take 1 shot a day for 2 weeks and then taper down to 3 times a week. My question is .will the b12 eventually stop working? I realize this may not be the cure , cause everyone on this forum would be out jogging. Will I have to keep upping the dosage to get the same effect? And why does b12,seem to make my symptoms go away..even if its temporary?