I'm not a therapist, so take my comments with a grain of salt.
Try this book: https://www.amazon.com/Understanding-Treating-Chronic-Shame-Neurobiological-ebook/dp/B015CLFM72
The author defines shame as "an experience of one’s felt sense of self disintegrating in relation to a dysregulating other". In more understandable English, this means that shame is the experience of feeling worthless, unlovable, not understanding how anyone could ever accept you, self-loathing, etc. because you fail to get the emotional connection and support you need from someone important. This disorders usually stems in childhood when a parent or caregiver fails to provide adequate emotional support to their child during times of distress. Because children look up to their parents and have to make sense of why they are not getting the support they need, the story they start believing is, as an example, "I am feeling upset that I failed to make the soccer team. I feel like a failure. My mom and dad aren't encouraging me at all, so therefore, I really must be a failure. I hate myself. I can't seem to do anything right."
Unfortunately, I think shame is often overlooked because it can manifest itself in anxiety, depressive, eating disorders, etc. which are classically more concrete, "tangible" disorders.
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