Hi. From what you have mentioned, it seems that you might be suffering from symptoms of depression. Wanting to be alone, consistently thinking about one thing or another, feeling irritable, not enjoying things you used to are all suggestive of depression. However, a detailed psychiatric consultation is required to confirm the diagnosis. With adequate treatment, you will start feeling better.
Next Steps
Seek a psychiatric consultation.
Health Tips
Start exercising daily. Talk to someone close about what you are going through regularly.