Hi ! You have not mentioned your age and if you are a habitual smoker or not. Possibly you have got a type of chronic obstructive pulmonary diseases, for example asthmatic bronchitis
. During acute exacerbations, this problem may give you a sensation of gagging.
If you have got chronic back ache, this may be a kind of arthritis
, for example ankylosing spondylitis
, which may be associated with some cardiac problems, which gives rise to gagging.
The blood in the stool may not be related to this and could be an independent factor, unless you are already taking some aspirin
like agents for any cardiac problem causing gagging.
I would suggest you get yourself examined by a cardiologist to exclude any cardiac problem for your present problems.
Wishing you an early recovery.