My concentration has been off recently, been vegetarian for a few months -could that have anything to do with it and are there any vitamins available?

Concentration: Depression and/or having something "on your mind" can detract from concentration. Vegetarians can get low on vitamin B 12. Consider taking a SUBLINGUAL B 12 supplement. Be sure to eat enough protein. See your doc to rule out health conditions. Peace and good health.

Balanced diet. : Maintaining a limited diet can result in deficiencies of essential amino acids, vitamins, protein or all off the above. Make sure you understand the substitutions necessary to safely cut meat out of your diet. ( beans, rice etc) If still having issues with a well balanced veggie diet see your md.