Your son is acting in uncharacteristic ways and displaying the following behaviors: Regressing, bursting into tears, and having difficulty concentrating.
Your post here, ultramarina, made me immediately think of one very uncomfortable possibility.
These behaviors are all typical of children who have been sexually abused.
What really alarms me is that you wrote:
�He is very good at chess and got a lot of attention for it last year, especially from coaches and other adults in his life. He began to see that he was unusually good at this thing. He has now retreated from chess.�
And:
�He chose not to attend chess camp after begging to go earlier in the year. This is very surprising coming from someone who used to eat/sleep/breathe chess.�
I am very concerned for your son. I am finishing my final year of doctoral studies in clinical psychology, and I have thousands of clinical hours working with children in various settings. Your son is showing classic signs, particularly in tandem with his sudden desire to avoid chess.
I hesitated to post this, because this is such an uncomfortable possibility. However, I felt I would be remiss to not say this to you.
I would be on alert for one of the adults connected to chess, who you reported in your original post had previously shown your son a lot of attention. Most importantly, I would urge you to take your son to a competent child psychologist to sort out the issue, whether it is indeed sexual abuse or not, and if so, who perpetrated it.
