Zantac for Reflux

Kate
Can anyone share their experiences with Zantac for reflux. The pediatrician thinks my LO has silent reflux and we just started the generic for Zantac. First dose and she vomited and she has only really spit up... she tends to swallow it. Will it get better??? I HATE to see her so uncomfortable with her feedings. How long did it take to see a change?