Taste. Lots of causes fro it. Sometimes just not enough fluids or acid reflux from your diet. See your doctor for blood tests to check your thyroid, anemia, b12 etc.
Bad TAste. This can have several causes. Strict diets offen cause some vitamin deficiencies and or mineral deficiency. A vegetarian diet may have marked difficiency in b-12 and other vitamins. Also if protein is not adequate, this can cause your symptoms.
See your dentist. Most common cause for this is infected tooth. Can also be related to sinus and lung infection. Not due to vegetarian diet.
Irrelevant. The change in your sense of taste may be caused by a variety of reasons; from medication you may be taking to dental problems. It may be a sign of a serious medical condition and evaluation by your doctor is warranted.
Vegetarian. As a vegetarian you still need regular tooth brushing, regular flossing, and regular dental care. Your diet can be higher in acids and this can erode tooth enamel. See a dentist.