It's possible. Sometimes the excessive screaming might wear her out enough not to have episodes like that every day, and she might sleep through some less painful episodes. I think it's worth a shot to try eliminating dairy from hers (and your) diet to see if that is what is causing her these fits.
Normally it will take up to 2 weeks to see a change, so you will have to wait for what lactose is in your system to clear and then hers. If that is the problem, it is totally worth the sacrifice in diet and the wait.
Check to make sure that she is gaining weight properly, and that she is having bowel movements. Usually with moderate to severe lactose intolerance, the baby will have explosive bowel movements, which may or may not have blood mixed in the stool (will be darker or green, but you still might not be able to tell just by looking.)
