You might be suffering from "low carb flu" (aka Atkins or keto flu) - you can check Google for symptoms. Your body may need more time to adapt to a lower carbohydrate intake, and if this reduction happens suddenly it can suffer withdrawal symptoms.
Make sure you're drinking plenty of water, and that you also have enough salt and potassium in your diet, as your kidneys will be flushing more stuff out.
But don't make the mistake of blaming diabetes or new diet with all problems, as there may be "normal" causes for your symptoms as well.
Robbity