@BrightRedLipstick specifically tagging you as Ds1 threw up before every morning exam for the real things from stress. It was the unknown of have I done enough, will I do well and be able to answer the questions? It was horrific for him and us. Staff knew him well enough that he wasn't ill just feeling the pressure. He didn't throw up at all for his A levels even though technically that was more life determining with getting into uni.
@pinkflop the most important one from the failing perspective is the English Lang as that is the one that he will be asked about in future. He is clearly a capable child with 7s for History as it shows he can write an essay. If you want a suggestion, and this goes to anyone on here, if you can get a copy of their mock paper look at that and the mark scheme to see what they should have written. That goes for any paper they want to improve on.
For English in particular, look up the past papers for their exam board and go through each question, figure out from the mark scheme what they are looking for. It is something they should be able to master to some degree. For narratives, have some descriptions of things already written about a setting, ie a house, a park, a forest, and then a person, plus weather. Weather lends itself to creating atmosphere especially cold or wet weather.
Revision is about chipping away. Mine couldn't get their brains to work after 9pm so didn't even try. They found coming home from school, snack and break, then revision until dinner so 2 hours ish a night. Usually in year 11 homework is either revision or show us the revision you have prepared. There are vast amounts of resources on YouTube from teachers. Find what method works for your child. And most of all, good luck.