If your girl has come to you in quite a bad state it may be that she still carries a worm burden, which could have been supressed during the winter/pregnancy, and now on the fresh grass she is suddenly overwhelmed. Fluke is another possibility - get a sample tested for both.
If she is not drinking either, keep her hydrated with something like Lectade (from the vets), by dribbling down her throat. If her temperature is normal she is unlikely to fight an infection, so something she has eaten (or over-eaten) may be the problem. Toast, crackers or oatcakes are sometimes still taken, or any fruit.
Hope she will get better, do you know how old she is?