I don't do well with doctor's appointments/procedure either. However, I have not fainted with my last few blood tests...and I am sure you will do fine as well if that is needed. Ask to lie down, that will help.
I am confident that you are not experiencing anything other than normal BP spikes due to anxiety. As the old medical adage goes ..try not to imagine zebras when hearing hoof beats.
Sending positive thoughts and prayers for courage and good results.
"Courage is not the abscence of fear, it is feeling afraid and doing it anyway!"
"Worrying does not empty tomorrow of its troubles...it empties today of its strength."
Corrie Ten Boom
Panic Syndrome recovery due to CBT