hi,
Welcome to Health Care Magic and thanks for posting your query , i understand your concern.
Sudden
weight loss could be due to various reasons.
By the history that you have provided in your query and by your symptoms i think you might be having
hyperthyroidism.
Pls get your thyroid profile done at the earliest to rule out the cause.
If you have been dieting in the past , there is a fair chance for you to lose vitamins and iron due to the weight loss.
Also decreased iron as in
iron deficiency anemia could cause weight loss too.
Consider getting your routine blood tests done as well and consult your physician with the reports.
Being vegetarian has nothing to do with the weight loss as long as you eat healthy and are on a balanced diet.
You could take
vitamin B12 and
iron supplements along with your food daily to increase the reserves if your blood tests reveal that you lack them.
Hope this answers your query satisfactorily, write back to me if you need further assistance .
Wish you good health. take care.