Night fall problem is a presentation of premature ejaculation. Anxiety is very common risk factor for it. The problem of digestion, not able to gain weight, weakness, all are indicative of underlying anxiety issue. I would suggest you to consult with a psychiatrist for its management.
Next Steps
With suitable instructions and medications, it can be cured. For more specific advice on management, you can ask a direct query to me here on Practo.
Health Tips
Dont worry. It can be cured.