My first diagnosis after going through your details is facial nerve
aberrant reinnervation.It is a condition that occurs when some one gets paralysis
of one half of face and recovers.During recovery,the nerves form wrong connections with glands.so whenever you eat,instead of salivation you get flushing.Paralysis of one half of face is called bells palsy..it may occur subtly even without you grossly noticing it.Iam sur it is not carcinoid
syndrome.so contact your neurologist
.He may advice you enmg or EMG,a test of facial nerve ,which supplies halfface either side.
all the best