Wecome to HCM
First check contents of medicine as Lansoparazole if given for fever? and vomiting
as acid suppressing drug there may be other drug for fever like paracetamol
or antibiotics if any.
if multiple drugs are given it is difficult to know which one caused allergic reaction
if only Lansoparazole is given allergic reaction is possible but is infrequently seen stop the drug and take a antihistamine drug and itching should go, if it persist and there are red eruption and swelling you should see a dermatologist
Hope it should be mild and she should recover quiickly.
Good luck to herl.