The symptoms as mentioned suggests that you might be having Irritable Bowel Syndrome
The medications namely IBset, Librax
& Colospa Retard are helpful in treating this condition whereas Razo prevents gastritis
So...the medicines given by your Doctor is correct.
But it has been found that these drugs cause constipation
as their side effect.
So...it will be better to consult your doctor to find out if there is any other combination of medications which can suit your profile.
Other than that...make sure that you are having fiber rich foods such as fruits & green vegetables.
Maintain adequate hydration...avoid smoking
Wishing you a good health.
Thanks & take care