In my opinion please try deep breathing exercise. Ly down on bed or sitting posture will help you relax your mind. Close your eyes. And focus on your breathing pattern. Inhale and exhale. 10 repititions you do. And see the difference. Take care. Consult for further opinion.

If these thoughts are occurring on and off, then probably you need not pay much attention to it as it common for everyone mostly. Being free leads to such kind of thoughts, try to engage yourself in some productive work which can help you get rid of your unnecessary thoughts. If these thought occur to such an extent that, you are work is getting affected, then consult a psychiatrist for further assessment and management. Best wishes

Read, walk, engage with something,learn new things