Sorry....just got back from taking the "old lady out".
This psychological stuff is not my area of expertise, but i cannot criticise any of the above posts,except the "tonsillitis post" which was clearly the natural history of tonsillitis and nothing to do with neurological pathways.
Counter-irritants are well known in medicine' that of providing another pain or irritant to neutralise the original pain.
https://en.wikipedia.org/wiki/Counterirritant
There are parts of the brain whose functions are ill understood, but start to play a part in overriding pain in moments of emotional stress.
A more eciting aspect of brain and mind pharmacology are Endorphins which are chemical substances brought into play by the brain in times of stress and anxiety, thus trumping any other pre-existing painful stimuli. Research into Endorphins is on going.
I am afraid that is my lot as i am not "big" on stress, strains and emotions.