There is a nerve which covers the area you are discussing, branches 1 and 2 of CN5 are opthalmic and maxillary divisions of the trigeminal nerve. It looks after the sensory supply to certain areas of the face. Testing of whether this is functional can include drawing a cotton bud lightly across different sections of the face and identifying sensation.
Problems with inappropriate nerve sensation can be controlled by some anti-epileptic medications such as carbamazepine or gabapentin.
A neurologist should be able to identify the cause and arrange appropriate therapy. In the meantime there is nothing additional you can do, apart from being careful with the skin in this area. eg hot water, chemicals etc could irritate without you being aware.
I appreciate this is very frustrating but a neurologist is definately the person to see.
Unfortuantly nerve problems can only be treated by a qualified practitioner, although your family doctor may agree to try you on the drugs I mentioned above for a while to see if there is any improvement.
In terms of the hot shower, I would reduce its impact on the skin but I do not think that this could be the cause unless it causes severe trauma and pain each time!