Check out pictures of orf (same as for sheep) on the internet and compare - she can get that from just nibbling on fence posts etc (if the field had sheep in before). It could possibly also have been brought in by your cow (who herself would be immune to it once she has had it). Orf is transmissable to humans, so please wear gloves when handling the blisters. It is best let to run its course, although the vet may prescribe a longacting antibiotic if there is a possibility of infection having entered through the cut. Nappyrash ointments (sudocream or similar) can be put ontp the blister to soothe. Orf itself is viral, and once they had it they will be immune for life. Goat No 2 may also get it at some point.
If she is eating her hay ok and drinking I would not worry, she should be ok in a couple of days time. Maybe put a bit of treacle into her drinking ewater to make sure she keeps drinking, and some aple pieces, banana or oatcakes should keep her going.
Also am a bit concerned that you say there is some blood around? Maybe she is also teething/loosing her baby teeth?