Gastric Problem

I m Siva Sakthi ( Male / 27 Yrs / Unmarried ) from South India.

My Physical statis : Height :174 cm, Weight :49.5 Kilo grams. Body type: very lean. Work nature : normal office work

I m having gastric problems with the following symptoms :

Abdominal bloating / belching after having meals.
Feeling stomach fullness after having small amount of meals.Bowel movement within 30 minutes to one hour after meals.
Motion frequency is high, usually in the range of 6-8 times a day and more aften gas is released, sometimes I have bowel movement but while attempting motion, only gas will be released.
I have heartburn and particularly after excretion, I feel very thirsty with heartburn.
I m underweighted and looks very lean body, as you can see above I m weighing only 49.5 Kg for a height of 174 cm ( however I m very energetic and generally does not have tiredness and also there is no vomitting problem, also my immune system is good as hardly I will get fever / headache once in 2 year)
Normally my body is heat and have excessive sweating, particularly I have abnormal sweating in toes and palms.

I have consulted with the Gastrentrologist and he underwent following tests.

1) Colonoscopy test found normal
2) Ultra sound scan found normal


I have also done Blood test and TSH with following results.

4) Thyroid Stimulating Hormone ; 3.32 uU/ml
5) Blood Glucose Randome : 77
6) Creatinine : 1.0
7) Bilrubin Total : 0.84
8) SGOT : 23
9) Total WBC count : 7400
10) Differential count WBC : P49 L45 E6
11) Haemoglobin : 14.9

The gastrentrologist says my problem is IBS and advised to take following medicnes for one month and suggested for re visit after one month.

a) Tab Pantium
b) Tab Eatul
c) Tab Normaxin

After reading an article about SBBO (Small Bowell Bacterial Overgrowth) , I think i m having SBBO and hence asked my physician whether it is SBBO, he denied that it will not bacterial overgrowth and defended that in case of SBBO, heamoglobin presence will not be 14.9, he says my problem is IBS.

In this situation I need the suggestion for my following questions.

1) What actually my problem is ? Is it SBBO or IBS or some other problem ?
2) Is the medicines suggested by him is good enough in my case to overcome SBBO / IBS ?, If not what are the medicines you would suggest to overcome this problem.
3) How long I should take the medicine
4) What should I do to gain normal body weight in the range of 65 Kg -70 Kg. At the moment, mentally I m very depressed with the fact that I m looking so lean and hence my marriage is delaying as girls in India do not like lean structured guys.
4) Pls advise my diet.