Fainting is not uncommon with gallbladder trouble. I used to faint over 100 times over a period of several years, before my first liver cleasne. After that I never fainted again. My blood pressure also used to be very low in general, and especially before and after fainting. It sounds more dangerous than it is. After 20-30 episodes I was no longer that scared. Since my liver was clean my blood pressure is perfect.
So, your solution is in getting your liver/GB clean.