What diagnosis do you apply for disability with?

Or maybe a general disability group. I know some people with ME in the U.K. who have found SCOPE supportive - it used to be a cerebral palsy charity but now widened its remit.

 

I was idly googling and found this interesting tribute by a charity, Validity, based in Hungary focused on mental health advocacy, but clearly working in Bulgaria and very connected to the disability rights movement there.
https://validity.ngo/2017/03/09/a-tribute-to-rusi-stanev/
Validity might be able to suggest an organisation that could help, or perhaps the Bulgarian charities* that are mentioned in the tribute, or the lawyer that is mentioned might be able to direct you someone:
*Bulgarian Centre for Nonprofit Law; GIP-Sofia

GIP-Sofia is presumably allied to the Global Initiative on Psychiatry:

I'm sorry if this isn't what you were after when you asked the question @svetoslav80. It's just that if I have learned anything about benefit applications from this forum, it's that they are almost always complicated and difficult, and getting help from someone who knows how to jump through the hoops is a good idea. And people with ME/CFS deserve some help to deal with the particular barriers we face.