There isn't much you can do about geographic tongue except avoid trigger foods/drinks, and avoid things that make it feel sore. I know it looks horrible... but unless you stick your tongue out at people they aren't going to notice! If you aren't aware of any triggers you may want to keep a food diary and see if you can find a connection between your eating habits and a flare up. Trying B12 couldn't hurt, (I've read that it can help) but I wouldn't get your hopes up; I have regular B12 injections and they do not seem to lessen my geographic tongue flare ups.
Welcome to the MedHelp forum!
Yes, low iron, Vit C or Vit B deficiency can aggravate the symptoms. Try and take a supplement for these and see. Also possibility of acid reflux aggravating the symptoms should be explored. It could also be due to contact dermatitis due to something that comes in touch with your tongue.
The best thing would be to consult a general practitioner or PCP and try and assess what is the cause of your problem. Then proper referral for concerned specialist can take things further and get you proper treatment. Take care!