Why is my dog acting weird?

All of a sudden, my female dog has been acting strange. This has been only going on today, but suddenly it looks like she's eating things off the ground, she has never done that before. We just recently just fed her, so it's not because she's hungry. When we took her outside, she started eating plants, which she usually doesn't do. When I tried to take her away from the plant, she growled and barked at me. My mother thinks she picked it up from our other dog, who is a male. Who eats anything he can. I suggested we go to a vet, but my mom isn't sure. Also, when she went outside, she started hacking but nothing came out. And she keeps putting out her tongue like a lizard kinda. Help?