I went to a very a difficult school and suddenly found that the single good quality I knew I had (being smart) I didn't really have at all. Every attempt to think hard became a reminder that I am a failure in this regard (and therefore have no demonstrable value as a human being etc. etc.). The existence of due dates forced me to think hard pretty often anyway until I graduated, but since then it just doesn't happen. Apparently this effect is pretty common for alums of [college], but usually it wears off after a year or so and it's lasted longer than that for me.

So yes, clearly an anxiety problem, and the video game suggestion would be a sort of exposure treatment. Can't afford to pay a third party to fix my brain (when I tried that in college I spent a month totally failing to communicate what my problem even was until they told me to stop coming, so involving another human is likely to be very time-inefficient), but there are workbooks and such that are said to be useful.