Is it normal to feel headaches, physical weakness, back pain, and blurred vision after watching pornography? Are these symptoms a touch from Satan? Will bathing with water and oil over which the Quran has been recited remove them? And does seeking ruqyah contradict the realization of Tawhid?

We do not have anything that definitively links weakness and pain to the aforementioned sin. It is obligatory to repent from looking at unlawful things and to resolve to lower one's gaze, because it is one of the means to chastity. Allah Almighty says: "Tell the believing men to reduce [some] of their vision and guard their private parts. That is purer for them." Seeking Ruqyah (Islamic incantation) and treatment does not contradict Tawhid (monotheism), for seeking treatment does not contradict reliance on Allah (Tawakkul), and the reality of Tawhid is not complete except by engaging with the means. Washing with water over which Quran has been recited is permissible, but in a place where it does not mix with impure water. It is better to drink it if possible.