Solution for Tummy Issue. This issue.

I have a tummy problem for quite a while (around 5-6 months). Because of which I regularly get pain/irritation in my abdomen - especially lower left side and upper right-left side. The keeps irritating most of my day with gas. And this irritation increases when I get excited or anticipate for something. The pain at times also extend from the lower back part to the tip of my anus. Also with this I get irritation/heaviness/pain in the upper chest part also. Most of the times, I feel bloated and have to pass gas or else I get the chills/cramps in my body. My stool pattern has also changed, going from thin/pallet like stool to loose/diarrhoea. For two months, i've taken treatment from family doctor,which he said it is colitis but i've got any relief after the treatment. Can someone please suggest how to solve this issue.