Are all of your puppy's immunizations up to date? Of course, there is always a chance that despite the fact she has been vaccinated, she could still contract something from someone or from somewhere. Dog parks are definitely areas of heavy challenge. Dog "leavings", despite the fact that owners hopefully pick them up as soon as they are dropped, can infect areas that your dog will instinctively sniff at. Vaccines sometimes, despite our best efforts, do not do their job, or rather, do not do their job as thoroughly as they should, and dogs get sick.
Keep an eye on her. It could be that the bully stick you gave her just didn't agree with her. Some dogs DO have extremely sensitive stomachs. My late Collie Katie had such a sensitive stomach that even the smallest scrap of anything other than the food she was accustomed to was enough to cause diarrhea that lasted two to three days before becoming solid again. My new little guy has an iron gut, and while he is only 14 weeks old, he has gotten into and eaten a couple of things that would curl your hair and suffered nary one ill effect from them.
I would follow Tony's excellent advice to withhold all food for 24 hours. Of course, as he also suggested, make sure she has an ample supply of fresh water during that time. After 24 hours, offer her about 1/4 of what you would normally feed her and give it a few hours to see how her body reacts to it. If she has a normal bowel movement, then you're probably home free and I would just not give her any more bully sticks. If there are still issues at that point, however, I would put in a call to the vet because it may be that you are dealing with something more serious than a dietary indiscretion. Please keep us up to date on how she is doing.
Ghilly
well if you started noticing this after you gave your pup the chew toy you should stop letting her play with it .....or maybe after the dog parks one of the dogs could have been ill keep a good eye on your pup and if things dont get better you should take him/her to the vet and discribe everything and im sure they will come up to a solution but is a possibly that your pup is depressed but since he/she is only about 6 months i would highly doubt it ....Hope everything goes okay !
I would suggest keeping her off food for 24hrs, which will give her digestive system time to recover, but ensure she has access to plenty of fresh water. If after 24hrs she still doesn't eat a normal meal, take her to the vet for further examination and diagnosis. Tony