Developed them during pregnancy with my son and wound up having it ripped out a month after he was born. The pain IS unbearable and sadly just about anything and everything can and will set off an attack. The last one I had that landed me in the ER with surgery was so intense that my husband came home from work early and rushed me in. It SUCKED. During pregnancy it's even more dicey since there isn't much, outside IV morphine and morphine related products that will even begin to take the edge off it. The best way to describe a gallbladder attack is feeling like a heart attack, just south of your chest and north of your stomach. It's HORRIBLE.
PS: avoid EVERYTHING fatty and greasy! You'll sincerely regret it. I don't care if that Chinese or Pizza looks FANTASTIC and you're craving it to the point of drooling, don't give in or you'll wind up in the ER having the worst attack of your life. Google the gallbladder diet. It MAY help. My final straw happened after eating plain oatmeal, though... It was seriously time for it to come on out.