I'm getting repetitive thoughts which are unusual for me having bpd wondering why I switch to extremes any advise would be appreciated?

Intrusive thoughts. Many possible reasons, from stress to med effects to wrong diagnosis or a new problem. Discuss with your mental health provider, so the two of you can get to the bottom of this and find some appropriate ways to help you deal with the intrusive thoughts. If the thoughts are very disturbing to you or you don't have access to a mental health provider, you may even need to go to the er.