Are the continuous problems, such as a sudden deterioration in financial and health conditions, that befell the couple after a period of success, due to envy (Hasad)? And what is the solution?

We advise you to maintain the established recitations for seeking refuge [with Allah] and to ask Allah for well-being. There is no harm in performing Ruqyah (Islamic exorcism), as it is permissible for both the afflicted and the non-afflicted.