Brief Answer:
Can be due to Gastric mucosa inflammation.

Detailed Answer:
Hi,
Thanks for query.
As per your history,You have urge to go to washroom after meals.It is one of the most important feature of irritable bowel syndrome.Mucous is a normal secretion of the bowel, although most of the time it cannot be seen. IBS patients sometimes produce large amounts of mucous,As in old age muscles become week,Anal sphincter fails to hold the large amount of mucous so it oozes out of it.
You are on a number of medicines from many years.These medicines release toxins which destroy good flora of intestine causing digestive problems.
Please Mention the duration from which you are having irregular bowel?

Now as per your query,
1)Yes it can be because of inflammation of gastric mucosa.It can be either Gastroenteritis ;An acute condition involving inflammation of gastric mucosa or it can be Irritable bowel syndrome.
2)Yes most of the time dietary changes are required to improve gastric problems
Few suggestions are
Eat simple,Light and easily digestible food.
Avoid Fatty and junk food.
Being vegetarian is good i don't think that being a veggie is responsible for yoou weekness,There are a number of countries in world where many people follow Veg diet and are perfectly healthy.
In your case most likely its improper digestion of food which is responsible for problems.

Tests adviced
Ultra sound Abdomen.
Stool routine and microscopy(To rule out bacterial or protozoal infection).
Digital rectal examination-To check patency of anal sphincterand rectal muscles.

Suggestions-
-Start taking a probiotic(Align) twice daily,Probiotics contains lactobacillus. These are good bacteria's help in proper digestion of food and will help to revive your depleted gastric flora.
Take Fybogel husk-Fybogel sachets and Fybogel Hi-Fibre sachets both contain the active ingredient ispaghula husk.It will improve your bowel habits.
-Take Pantoprazole 40mg once daily empty stomach for relief in Gases and fullness.
Apart from medicines,
-Add fibres to your diet. Fiber adds bulk to your digestive system. It is broadly accessible in grains, vegetables and natural products. Concentrate on soluble fiber.
-Consume plenty fruits and vegetables.
-Take carbohydrates in required quantity like bread, rice, oats, pasta, potatoes, and plantain.
- Include substitutes like soya, rice or oat, milk and yogurts that are rich in calcium in your diet.
-Take a limited amount of foods high in fats and sugars..
-Drink a lot of liquid, no less than 66 ounce every day.
Regards

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