What should I do about my intense fear of contracting AIDS, and the sorrow and worry that have afflicted me after being cut by a razor whose cleanliness I am unsure of? Is this a punishment from Allah for my shortcomings in worship?

This issue is about obsessive thoughts and delusions, and their cure is complete disregard for them, and not paying any attention to them. There is no harm in consulting a doctor, and in increasing the remembrance of Allah and His worship, and in maintaining prayer and other religious obligations.