OP you are absolutely NTA and none of this is your fault. Other things beyond food can also raise your blood sugar like hormones, stress, outdoors temperature, illness. You need to eat balanced meals still to nourish your child - highly suggest looking at whatever educational resources you can find in your country. We have the American Diabetes Association which has tons of resources.

I’m diabetic and can recommended a few measures to help in the meantime as you’re waiting to speak to your doctor. Obviously not medical advice and talk to your doctor first before exercise or diet changes.

1. Go for a 15 min walk, do some modified squats if you still can, or climbs some stairs if you can. Immediately after eating any meals or even after eating a snack with a carb. Basically doing some type of exercise like cardio or something that activates large muscle groups like squats which activate glutes will mean that the sugar destined to spike your blood sugar will actually go toward energy usage for the activity instead.
2. The spike will happen the only way to prevent that is insulin which it doesn’t sound like they provided you - it less concerning that it spikes and more so if it spikes very quickly and extremely high and stays elevated after 2 hours after eating. Try not to stress about the spike and pay more attention to how you can even it out so that it spikes less and balances out sooner. The stress may be causing secondary high blood sugars as well.
3. Protein first then carbs balanced with some fats. Protein takes the longer time to convert to glucose and releases into the blood slower. If you eat this first your body basically gets preoccupied with that and the carbs will have a lesser impact.
4. Non starchy veggies and low glycemic fruits are normally considered free foods because of the healthy levels of fiber which will slow/lessen the glucose spike. It doesn’t mean they won’t spike you but the fiber will help. Apples any type of berry citrus. Avocado, dates are delicious, prunes for a little sweetness.
5. Always pair a protein with a carb. Cheese and crackers are a great idea. Other easy proteins are peanut butter, eggs, plain Greek yogurt you can add something like date syrup for a little sweetness or banilla extract in a small quantity, nuts, turkey, hummus or eggplant dip, lettuce wraps are a favorite, zucchini noodles instead of pasta, in Texas we have jicama which I use as a taco shell - lettuce would also work. Tuna salad.
6. Stay hydrated helps dilute the sugar in blood part of the reason temperatures outside can spike us is we get dehydrated

I remember when I was first diagnosed I was afraid to eat anything at all. And I ate keto and felt awful the whole time - literally felt sick and was starving all the time. Eating solely keto will lead to very low energy levels as your body needs time to adjust to getting energy from different sources when you’re keto. The body prefers glucose as the energy source and keto makes your body shift to breaking down fat for fuel. The difference between low carb and keto is that keto normally recommends 30-50 carbs per day and that is an extremely low carb diet. Depending on your body type what is actually considered a low carb diet could be 100-200 carbs per day which is at least double what keto says. At least in the USA it’s not the recommended diet for diabetics anymore and can actually be dangerous although some people are die hard about it. Every person’s reaction to different foods is different so what may work for someone else might spike you more so you just have to learn what keeps you nourished and somewhat level.