Insomnia

Okay, so after weeks of trying to get a docs appointment, I finally got one on Thursday for today... In the last 2/3 weeks I've had maybe 3 days worth of sleep... I woke up extremely late one morning and ever since then it's like my body clock has done a complete 12 hour swap round like day time is meant to be nighttime and night time is meant to be day time... I've done everything I possibly can to try and get it back to normal but nothing's working, I have my appointment at 9:10am today to see if here's anything they can do to help me but this is getting way out of hand! Does anyone know what may be causing this?