Severe stomach ache and motion. Advice!

I have been experiencing quiet often very severe stomach ache as soon as I eat anything and immediately I will have to poop. It aches alot while passing motion after that I become fine. I become fine and again after a month I face the same issue. I do not have typical diahrea or vomitings. But I have stomach ache while passing motion. Most of the times either I get constipated or stomach ache and bad smell motion. I feel indigestion and cramps have pukish feeling because of which I am unable to eat. If I eat my stomach aches and immediately I have to pass the stool. it's like this since a week. I usually have acidity too due to my irregular eating habits. The upper area of the stomach seems to hardened and the stomach bloats. Since two days I started Bifilac. Kindly advice!