Hi. From what you have mentioned, it seems you are remaining preoccupied with thoughts which is leading to your inability to focus and concentrate. Although more details would be required to come to a conclusion regarding your diagnosis, depression is definitely a possibility. You should consult a psychiatrist at the earliest to get yourself evaluated. Accordingly treatment can be initiated.
Next Steps
Seek a psychiatric consultation. You can consult me directly at my clinic if you wish to.
Health Tips
Earlier the treatment is started, better is the response.