Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain excessive gas at the age of 12 years along with cramps can occur due to causes like change in dietary habits and increased fibre intake in diet,indigestion,constipation, lactose intolerance, celiac disease, irritable bowel syndrome, stomach infection leading to Gastroenteritis.. As it is just 3 days for you to have these symptoms you need not to worry as there is not necessarily anything serious that needs to be worried about.. You can avoid taking a lot of fibres in your diet.. You can add up Probiotic like Yoghurt in your diet but on the other hand avoid intake of excess of other dairy products.. You can drink plenty of warm water .. Take a light diet and avoid heavy and spicy meals.. Eat every 2 hours in small portions.. Eat slowly as faster eating can entrap excess of gas and cause burping at later stage.. You should also take short walk after meals.. Limit intake of carbonated drinks or cold drinks.. You can also take Simethicone as it will help in reducing gas formation and ease its elimination.. In case if you still do not find improvement consult a Gastroenterologist and get evaluated and a thorough clinical evaluation and investigations like Colonoscopy and blood tests can help in diagnosis and can treat you according to the cause.. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.