What is the solution for someone who suffers from obsessive thoughts and psychological distress that affect her prayers and acts of worship, and is she sinful for not consulting a psychiatrist?

What you are suffering from may be mere whisperings (waswasah), and its cure is mentioned in Fatwa No. 59951. We advise consulting a trusted psychiatrist, bearing in mind that not consulting a doctor is not considered a sin unless one is certain of perishing, as stated in Fatwa No. 44571. Fearing Allah, seeking refuge in Him, and avoiding sins are reasons for the expansion of the chest and the removal of worries. For more information, please see Fatwa No. 71616.