With low self-esteem some symptoms would be that you don't accept compliments you will say thanks but no I am not for example
stress- you lash out and sometimes you don't even know why
Depression- You stay in your room all day to avoid people. You also aren't interested in things you used to be interested in.
Mental disorders- depending on what mental disorder you can have anxiety (common with general anxiety disorder and OCD among others) Schizophrenia You can have inappropriate reactions like laughing if someone falls down and cried or at a funeral.
These are all from what I live with or have learned in psychology I hope this has helped if you need more examples of mental disorders let me know!
