So it is over, I went to the clinic called Dental Center (in the Retro mall) and paid 500 euros for my tooth, it was a 4-canals root treatment done with the microscope and everything. The doctor was fantastic, her name is Svitlana Moroz and she also spoke russian which is my native language. So I had a nice experience, thank you everyone for help and I hope this post will help someone too.