Hi there,
I could be wrong - and you may want to check on the
http://www.cryingoverspiltmilk website, but I don't think that any of the medications stop/minimise the vomitting/spilling. They just help to clear/stop any inflammation and reduce the acidity (which causes the pain, arching, screaming etc). So even though she is still/just started spilling, I don't think that necessarily means that her dose should be increased (although it still may need to be - the website has good guidelines about dosage with weight increase).
From what you've written, it sounds like things have settled down a bit, and the zantac is doing its job.
Good luck!