I don't know. Corticosteroids can have magical effects in your body if used properly to calm down autoimmunity or inflammation. Consider that many doctors are reluctant to prescribe them unless they have a clear justifiable reason, which they don't in long COVID since everything is ""fine"".

300€ is a lot. But i paid 120€ for a 30second visit plus 1 hour to explain to me how i was imagining things, and the only things prescribed to me were two overpriced over the counter supplements that i didn't even bother to buy and waste my money on. Italian healthcare here.

I would try the treatment. I'm not sure it's the best one, but steroids make sense.