Is the problem of lack of continuity in work, loss of passion, decline in skill level, forgetfulness, and inability to acquire knowledge attributable to envy (Hasad), and what are the signs of envy?

We do not have what definitively proves that you are afflicted by envy or magic, but we advise you to regularly recite the prescribed remembrances (adhkar) and protective supplications (ta'awwudhat) for protection. Be careful not to accuse your friend of evil without clear evidence, because negative assumptions are sinful, and the sanctity of a believer is greater in the sight of Allah. Continue with ruqyah (definition) (Islamic exorcism), and there is no harm if someone else, from among the righteous who adhere to the correct creed, performs ruqyah for you.