You need to go out there and try to locate what she got into, and then you need to take her to the vet. Obviously, something got a hold of her. I wouldn't take a chance with trying to fix this at home. Hope this helps, good luck.

 Sounds like an allergic reaction to something which she has come in contact with. If you take her to a vet they may be able to give her something to reduce the swelling etc. If she seems to be getting better already you may find it goes away of its own accord but watch out for swelling of the tongue and problems breathing which could also be signs of a more severe allergic reaction and would definitely require an emergency trip to the vet. Hope that helps