Underweight. Problems mostly okay. or!

Hello I am Milan. I am 29 years old male from Delhi. I have been getting weight loss at least 6 kg. science January 2016. now my weight is 56 kg. I have done all the tests related to my digestion issues or blood, stool,Thyroid, HIV, TB, Ultrasound, liver test etc. All are normal. Some doctor says its IBS or some are says I have tension or anxiety ( Yes I have but I think its all related to my problems like I keep thinking every time about my bad health) And honestly I felt the all IBS symptoms in myself. I had continued all medications suggested by my doctors. Yet no significant change. I had cervical issues, and middle back pain sometimes and had MRI in past (doctor says it is very normal now, not have any nerve issues in MRI). I felt sometimes heart palpitations and I felt nevus then (which I felt in past days too when I was in good weight ) I am doing yoga and asanas. And its normal. But, one thing I noticed that when I felt neck pain then all my digestion problems mostly okay. Or