fruitpie Oh no! It sounds like you're struggling with the pressure of the task rather than the actual writing itself?
With our students who struggle with the pressure, we suggest gently desensitising them to the pressure. For different students, different things trigger the pressure. Some students finds the silence really triggering, other students find the presence of a clock triggering. I suggest thinking about your experience and identifying what's exactly making you stress out, then findings ways to gently increase it.
For example, let's say it's the sitting on a hard chair in silence that's difficult for you. I suggest sitting on a hard chair and writing without a timer, then with a timer for a long period of time (eg 30mins for a BP), then gently bring down that time limit, then towards the end, put on some noise-cancelling headphones while sitting on a hard chair writing within a tight timeframe.
I hope that helps! Brain farts are awful and if it makes it any better, you're not the only one experiencing it 🙂