I hope you didn't think I was implying that you have mental health problems keberoxu. It's just that your distress comes across in your posts, and I was musing about what might help you.
I think the fact you suppress any spontaneous self-expression is a result of being over-controlled as a child (I think you've mentioned this)
Such ingrained behaviours are very hard to modify, but as you say, the result is an inner anger which simmers away and causes reactions in physical health. Is there any way you could let out all this in a safe environment? Vigorous sport, the gym, writing down your pain in poetry or autobiographical notes for example? It would be like lifting the lid off the pot for a bit and letting the steam out!