Dear doctor, i have a hair loss problem. i am a vegetarian (i don't eat eggs and fish). can my diet be a reason of this problem ?

Possible nutrient: deficiency. Virtually any nutrient deficiency can contribut to hair loss. Examine your diet closely to ensure that you are taking in adequate: calcium, iodine, protein, iron, Omega-3 fatty acids, Vitamin B12, Vitamin D, and Zinc. See the following article for basic guidance: http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/vegetarian-diet/art-20046446?pg=2