Well, I'm finding your post quite difficult to understand, so I'm not even sure if I'm answering the right question.
Anyways, is she formula-fed or breastfed? Judging by her age, reflux is a reasonable possibility. You say she had the vaccinations last Thursday and was essentially fine - I would say it's a safe bet that the vax aren't related to what's going on. At her age, it could be colic, or it could be reflux (which is quite often originally diagnosed as colic and turns out to be reflux). Remember, she's little and her tummy is still maturing.
I wouldn't freak out. If the Zantac gives her some relief, then reflux was probably the right diagnosis by the doctor. If you aren't seeing a change in a couple of days, take her back to the doctor. But be aware that at this age, fussiness can be a major issue that a lot of new moms have to deal with.
There are lots of things you can do to get through a rough period like this - try reading Happiest Baby on the Block for the five S's, which have saved the sanity of many moms on this board. Get a sling or other baby carrier if you don't already have one and use it as much as you can. Don't be afraid to go back to the doctor if you aren't happy with the diagnosis.