Hi, My 18 Yr Old Has Been Diagnosed With Deficiency

hi, my 18 yr old has been diagnosed with deficiency in vit b12 and received 2 injections of it. one wed and one sa. wed had side effect of aches and pains then improved and was more energised. sat injection was less sore and seemed to improve. she went out and had alcohol on sat night and now is feeling even worse. is this the alcohol or something worse.she is due another injection of vitb12 tomorrow