It is normal to freak out at anything and everything**. I almost convinced myself that I had a problem about 2 month out of radiation, when I got a lot small blisters (roof of mouth) every time I was eating something.. (=big nothing, minor salivary glands working again)

Re Pet
1) no exercise and NO running around and hurrying before the scan. This includes getting to the center.
2) you may get an oral contrast agent to drink before the scan (for CT)
3) they will measure your blood glucose level and if ok inject radioactive glucose. No big deal, do not freak out because of the strange syringe.
4) you the rest for 45 minutes or so. Try to sleep, you should not talk
5) then the scan you, try to stay still and do not move your tongue/chew or swallow too much. Unless they tell you otherwise breath normally.
Depending of the scanner this should take 20-30 minutes.
6) then get coffee etc!

Best!

M

** of course that presumes that I am halfway normal...