Help!?

My cocker is 6 months old, so I know she’s going to have a ton of energy. She has 8 acres she gets to run around and play on, so she’s never bored.

She has started to get a little aggressive with playing and has started nipping and growling at us. We took her to get groomed today and within 10 minutes of her being there we got a call and she said she can’t groom her because of how aggressive she was being. We now have to get a sedative from the vet for when she gets groomed. What can I do? I don’t want her to get too out of control, especially since I have a toddler.