Hi Lowlow, thanks for coming to the forums.
What you are experiencing is not an overreaction and I can only give you my suggestion of what's happening but I'm not a qualified doctor and I can't diagnose you, your GP needs to do this.
The same happens to me and have had them for a long time because OCD comes from anxiety and are known as 'intrusive thoughts' where you imagine these persistent thoughts.
Your doctor can prescribe medication for this, however, sometimes it eases off but it's best to talk to a psychologist about them, and don't be afraid to do this, they've heard it all before.
If you ask your GP about the mental health plan this entitles you to 10 Medicare paid sessions.
Let us know what you think.