I quickly grabbed Sydney and smelled her face (yes, this is probably gross for all the non-dog owners on my friends list) and realized that she had eaten ALL of the cookies - probably while we were at work! :P I scolded her for a bit, cleaned up the mess, and tried to get her to drink water. I was afraid that she'd get sick from the chocolate, but she seemed to be fine.
Then later this evening I noticed while I was walking up the stairs, that she wasn't following me like she usually does. :( In fact, when I turned around, she was walking up the stairs in a criss-cross pattern, similar to when she was really ill last year. :( That got me really worried.
Mark and I spent the next half hour or so observing her and contemplating whether or not to take her to the vet. She just sat and looked at us and wouldn't get up to play with her toys if we threw them or played with them in front of her. When we got up and walked away we noticed she was limping, and favoring her right leg. We were rather relieved that it wasn't "chocolate" related, but then began to worry about whether or not she broke or sprained something in her leg.
We finally ended up calling the vet to make an appointment, we changed, and carried the dog down the stairs. Once we were downstairs, I picked up her leash and Sydney ran away from me and wagged her tail! I walked away and she followed close behind me - she was still limping, but she was well enough to keep pace with me. Mark called the vet and explained that we wouldn't be in - that our "pesky little critter" must've known that we were going to take her to the vet because she scurried away from us when it was time to go. :P
I'm still worried about her leg and will keep an eye on it, but I don't think that a late night vet visit is necessary tonight. Thank goodness!