I am 33 yrs old guy. My height is 5 feet 7 in and weigh around 55 kg. I always was underweight. From past few years I suffer from bowel problems such as loose semi stools, feel tired and mentally also I feel tired, lack of concentration, poor memory, low grasping power, anxiety. I feel I am not able to absorb nutrients properly. I did consult a gastroenterologist but problem persisted. Later did preventive health test. The report shows low vit b12 and vit d levels. I want to know is these low vitamin levels causing problems because I am not able to think clearly also. Hope my documents are available. Please help me out.