Is a sheikh who asks a married woman to wear a belt with a dead scorpion on it to facilitate pregnancy, and to name the newborn "Sanad," considered a charlatan, knowing that there have been previous pregnancies for her even after she disobeyed his instructions?

The aforementioned Raqi (exorcist/healer) is a charlatan. It is impermissible to believe sorcerers or act upon their directives. Believing in benefit from something that has not been sanctioned by Islamic law or by common experience is polytheism (shirk (definition)). Whoever relies on a means that Islamic law has not established as a means is guilty of minor polytheism (shirk asghar).

You must seek help through patience, prayer, and supplication, and persist in reciting Surah (definition) Al-Baqarah and the legitimate Ruqyah (definition) (Islamic incantations).