I get negative thoughts periodically. Is this a mental illness?

Hello doctor,

I am having repeated thoughts in my head from the last four months. This problem started at the age of 13, but on a periodic basis like three to six months. After that, it becomes normal. When I am in this phase, I have scary thoughts, feel like mind is racing, have wavering thoughts and I feel that I am actually in that situation, talking inside my head, and solving a situation which my mind has created. I cannot enjoy the present. I feel stuck with this mental condition. Generally, I avoid some kinds of situations and people, because I feel that if I go to some places or deal with some types of persons, then I might face negative thoughts. I do not know what this is called. Is this some kind of disorder or mental illness? Is this a rare or common issue? Please guide me on this problem. Waiting for your answer.

Hello doctor,

Thanks for your interest in my case. This episode has come after two to three years and has lasted six months. I would like to give a few examples of my thoughts. One of the repetitive thoughts is that if I go on a vacation, I will lose my wallet or all other belongings and get stuck at that place. I cannot get back home on time. Another one is about my business. If I dealt with a particular person and did not complete that order, I get thoughts about being stuck with the problem for a long time. The thoughts become deeper and get to the micro level. During the episode, sleep is usually normal, but sometimes it is less, I feel angry and do not like to buy new stuff. Of late, I want to live alone and do not want to talk with new people. On some days, these feelings continue throughout the day. Sometimes, I feel them early in the morning or after sunset. I am scared.