At 10 weeks old, I would be very concerned with taking her to a park and running around so much outside where she can catch a whole host of things that are not good. She is still so very young.
When cleaning her behind, scent free baby wipes are a good alternative. After ruling out any medical issues with your vet, a higher quality food would be a good start. But don't switch foods suddenly or often as that can cause intestinal stress (poopy problems) as well. There should be a sticky here in the health and diet section on good quality food brands.
http://www.yorkietalk.com/forums/yor...e-samples.html
One other note, if your vet said it is common for Yorkies to have issues with number #2, it sounds like they aren't really sure what to do and don't know alot about small breeds. No offense, but I would look for another vet, especially if she is that uncomfortable.
What are they using to treat the yeast infection? Did her problems start after that or has she been straining since you got her (when did you bring her home?)
ps: welcome to YT, hope you'll browse around and find loads of good info to help you with your new baby
