Oh man that sounds rough. Sorry the specialists in your aren't equipped to check your REM cycles and things of that nature.

It sounds like a frustrating situation to live with and I'm not sure I have any advice other than ask your doctor about shift work disorder.

What you're experiencing sounds very similar to what happens to people who work 3rd shift for a long time and can't get their sleep schedule back on a day time=awake schedule.

Sleep issues are incredibly complex however and its something a doctor who has your medical history can better address, but having some terminology to describe your symptoms can help them help you. I hope you find a solution soon