Hello Sir, Problem : Being underweight, sir i am 5 feet

Patient: Hello Sir,Problem : Being underweight, sir i am 5 feet tall but 37kg by weight. 4-5 year back, i passed through disease Tuberculosis, from which i recovered successfully after completing 6 month course. Sir i was fit some year ago but for 2 years i have a continuous health decline. I had depression, which i recovered from, Now i eat well, sleep well and also not that physical hard work, but yes I have some cough problem which comes maximum 2-3 times a day very lightly, but it lost for 2-3 months. recently I made check up for tuberculosis, but all test were normal.Sir please suggest me what to do to overcome from being underweight.Thanking You.Shalini Prasad