Many times after a huge crisis such as psychosis disorder, people go through a process of collecting they're soul pieces. The new feeling of being with such a horrible secret and a terrible experience behind them, frequently cause them to feel not belonging to they're surroundings.
For example, when a sufferer sits behind a table in a coffee shop, he usually feels like not being a part of its surroundings. If he sits alone, then his feeling is being intensified. He sees people who read the paper, talking to they're friend, reading a book and he has nothing to occupy his mind beside of his recent disorder.
In order to remove that feeling, the sufferer should first cause himself to be busier with other occupations that would distract his mind from his disease. Things like hobbies, doing gymnastic, writing a journal, painting, crafting and other occupations, would get him to think of other things aside of his condition.
If you feel like not belonging when you are alone at the cafe, maybe it is a good idea to go there with a friend or a loved one, and to avoid attending they're all by your self. Try to keep yourself a company in such places. Don't be alone if you know that it would cause you to think of your disorder.
In time, you will see that this basic feeling of not being belonging to places and crowd would change due to your other interests in other life activity such as being previously mentioned.