This is Dr. David
I am glad you are getting stool testing and blood work.
buscopan is hyoscine butylbromide 10mg and is used for IBS in the UK
are you in the UK or USA?
loose yellow brown stools are usually not a sign of cancer, but can very well be a sign of IBS or a bowel allergy
you could be allergic to gluten wheat protein in breads and pastas which can cause loose stools
allergies to milk sugar lactose or milk protein casein can cause loose brown stools as well.
these need to be checked for
you should keep a food diary of what you eat and when your symptoms are worse and see if you can find out what food cause worse symptoms and then you might have to avoid then.
the stool blood testing and blood test can give more information
let me know if you have questions.