SCM, as mentioned before, you need to get some help for coping.
Please contact both your GP and your nurse specialist.
There's nothing to worry about the PET scan procedure. They won't be able to give you any results on the day - it will take time to be processed, reviewed by a radiologist, and then passed back to your multi-disciplinary team to be discussed in their next weekly meeting. It's pretty typical to take around 3 weeks for the results.