Welcome in H.C.M.
I have gone through your query regarding watery discharge from your right nostril
, though you have some neurological and heart disease
After considering your symptoms and co-relating them it becomes clear that you are most probably having CSF rhinorrhea
because your discharge is unilateral (Right sided only) unlike allergic rhinitis
where as a rule discharge is always bilateral (from both nostrils).
This may be further confirmed by cytological and biochemical examination of discharging fluid.
Regarding your lump at the back of neck , it may be meningocoel because it's size changes with change in pressure.
Though your problems may be clarified by a through clinical examination by ENT doctor & Neurologist