fainting usually happens from low blood pressure, so a cold skin and pale feeling. it can happen when people get into deep discussions about disease, medical or blood. It is quite common for people in hospitals to suffer this. It can happen if people are dehydrated and low on sugar as well.
high blood pressure causes headaches, blood noses, tiredness, tension, frustration. anxiety, warm skin.
when I have my blood pressure taken, pressure on the arm and veins, I usually faint or come close to fainting, very low blood pressure reaction. which is a white collar syndrome thing, some people have this with needles. but you can also have it with blood pressure testing.
nervousness and panic causing low blood pressure would make you faint if you're reaction is a dizzy cold feeling.
nervousness and panic can also cause high blood pressure, headaches and tension.
perhaps see a doctor for this.