Weakness and heavy head. Be the problem?

I am suffering from a very strange problem. It started 2 months back, suddenly one day i got some pain in my stomach along with bloating and extreme burning sensation in whole body along with dizziness and increased heart beats. I thought it was gas and took some home remedies for gas. After 1 hour the issue reduced and went to sleep. Since the very next morning i have been facing inconsistent stools along with stomach bloating and heaviness. Also i am facing weakness, heaviness in eyes and dizziness and sometimes burning sensation in body. I have also lost 6 kg weight in last 3 months. I have visited many doctors, some say it is anxiety others say stomach infection. I have taken some medication also but no major relief. I have also done many tests like CBC, LFT, KFT, ECG, TSH, B12, Vit D etc all are normal. Please suggest what could be the problem? Is it related to nerves or digestive system or some other and which specialist should i consult.