Hello, Peaches86, and welcome.

It's not easy to guess what might be the problem, but I can give you one thing that might cause it: it could very easily be the acidic residue (or ash) which all medications leave behind in digestion. The buildup of that over a period of days (before the kidneys can catch up to remove it) can cause intrusive thoughts.

I have found over the years that cutting 1 or 2 lemons in half and squeezing them into about 8 oz of water and drinking that will help reduce the acidity of the fluids and tissues, calming the thoughts strongly. If it hasn't worked within 4 hours, repeat the process, and you should have relief.

It does work for some bipolar patients. (I keep about a dozen lemons in my
refrigerator at any one time!)

Take care and I hope you feel better.

Please discuss these thoughts with your psyciatrist because some other chemical problem could be going on that he needs to investigate with you.