It's essential to understand that I cannot provide a diagnosis, but I can suggest that what you're describing might be indicative of certain mental health concerns.
Feeling like someone is watching you even when you are alone, constantly checking for others, feeling paranoid, and experiencing insomnia can be signs of various mental health conditions, including anxiety disorders or paranoia-related conditions.
If these feelings and behaviors are causing distress or impacting your daily life, it's crucial to seek support from a mental health professional. They can provide a proper evaluation, offer a diagnosis, and create an appropriate treatment plan if needed.
Remember that seeking help is a sign of strength, and you don't have to face these feelings alone. Reach out to a mental health professional, such as a psychologist, psychiatrist, or counselor, who can provide the appropriate support and guidance based on your individual situation. They can help you understand what you're experiencing and work with you to find effective ways to manage your feelings and concerns.