Need opinions on aggression
I have a GSD (possibly mixed, my profile pic is of her) female, approx. 6-7 years old, that has started to become aggressive more (slowly) over the past month. We got her on 7-04-12 and the vet then estimated her to be 4-5 years old. Over the past month, she occasionally would growl at my son (who's 3), myself, and also she growled at my mother in law for telling her to go lay down for chasing my cat. Then a couple weeks ago, she nipped at my son and then again today, she nipped my hand when taking her by the collar so I could put her in our den when we were leaving (she stays out in the room with a baby gate up, we've never kenneled her). I wasn't being mean whatsoever, just trying to leave the house so I went to grab her collar and she nipped me! She has never done that before. My mom suggested to take her to the vets and get her tested for thyroid problems, which makes sense because she also has a few other symptoms as well. Except we don't have the funds to do so until income taxes come back... Meanwhile, I don't know what to do because I can't have a dog that bites and growls as I have 2 young children and their safety always comes first. But I have a terrible fear of re-homing her because A. I love her to death, she's a part of our family and B. I don't want her to end up in a bad home as well. What would you do?