Because low carb is the way the vast majority of type 2 have found that works best after trying and failing with the sort of advice you were given. Yes I think you should definitely try it. You did ask and get similar advice on another recent thread. You’d expect bgl to fall, in immediate response to what you (don’t) eat.
Anyone on anything other than metformin should discuss it with their dr first though as too much medication at the same time might lead to a hypo and levels need monitoring closely to keep the medication at the appropriate dosages for the new diet.
The unwell thing you mention is carb or keto flu. It’s fundementally sugar withdrawal, as the carbs are instantly turned to sugar in your body. It can be minimised by reducing carb levels slowly, ensuring fluid intake is high, ensuring electrolytes (salts mostly magnesium and potassium) are maintained and increasing fats to provide energy instead of using carbs. It sounds counterintuitive to all we’ve been taught for decades but the NHS support it as a strategy at long last after lots of studies showing it works.
The other thing that can happen is when you are used to very high bg levels you may (not will) suffer false hypos. This is where your body has a tantrum at you taking its sugar fix away and doesn’t like the better lower levels and pretends to have a hypo giving similar symptoms to the real thing but it’s not dangerous in itself, just unpleasant. If you can treat it like a toddler and ignore it and they’ll stop as your body acclimatises to the new levels. If it’s really horrible a ‘small’ amount of carb will take the edge off without recreating the problem you’re trying to get rid of.
See the attached for more info
https://www.diabetes.co.uk/forum/blog/jokalsbeek.401801/ for info including low carb made simple
And
https://www.diabetes.co.uk/forum/category/success-stories-and-testimonials.43/ to show it really works and for motivation
and
https://www.diabetes.co.uk/forum/threads/what-have-you-eaten-today.75781/ for food ideas
also
https://www.dietdoctor.com/ for more food ideas and general info of carb content of foods.