I agree that there's nothing shameful about psychosomatic illness and that it is normal.
Deleting the external world and all of its causal influence is a very religio-philosophical move. (Academic philosophers who do this tend to be Buddhists or Buddhistic). I've met many academic philosophers who reject such an idea. Constructivism might be true about some things (mathematical entities) but is probably not true about subjective experience, and is almost certainly not true about conscious awareness in the psychological scientific sense.
Think of it this way. The brain and all of the neuro-cognitive (including emotional) information processing in it is part of nature. (I'm using the hyphenated term 'neuro-cognitive' to keep the discussion sane since there is no non-neurological cognitive processing). It's not outside of nature or causal closure of/under the physical. Everything that is happening in one's neurology - including anything ascribed to epiphenomena - is reducible to neural information processing of physically reducible information (no physical structures - no information).
All of the information processing happening in one's neurology - which is part of the physical structures of nature - is happening to one's neurology. Unfortunately, that doesn't necessarily allow for 'downward causation'.
None of that is constructed subjectively and it certainly isn't made up in the sense of being consciously invoked. It's 'made up' of causal neuro-cognitive processes . This is made obvious by everything from lesion studies to Alzheimer's disease. When the physical neurological information processing substrate is damaged, cognition and subjective experience are directly affected.
