My first thought is that if things were going well for three months and then they changed, something most likely changed in her classroom, or among peer relationships. Have you tried talking to her teacher, other parents, your dd - not so much about what's not working or her behaviors etc but just about what's up in school? I don't know if this is something you already do, but one of *the* most helpful things that I've found as a parent is to ask my kids to tell me about everything they did in school that day when I pick them up at the end of the day. This is beyond boring and annoying to them, but it's really helpful in tying what's going on with my kids with what's up at school when there is a connection.
The other thing that I thought of was kindergarten girls - even in kindergarten, there were girls who would bounce back and forth between clickish-type relationships on the playground and in the classroom. My oldest is a ds, and this *never* happened with boys at any point as far as I've seen, but it's been ridiculous a few years here and there among my dds' peers (girl-peers). My oldest dd had a best friend in kindergarten for a few months who then suddenly turned and excluded her from being a friend. Other friends liked to form "clubs" at recess (even though the school policy forbid it and the school staff at recess tried really hard to help the kids *not* exclude other kids). I would want to dig a little just to make sure that you're not missing something that has happened socially - another child's behavior or exclusion of your dd etc.
You are probably far enough south that SAD isn't an issue, but there may be other seasonal things that could impact your dd. Allergies are the first thing that came to my mind - pollens are seasonal, as well as molds, and allergies also flare when children start spending a lot of time in houses with windows closed in the winter time (poorer air circulation, more dust in the air etc). One of my dds was extremely impacted by a mold allergy at your dd's age - and it absolutely showed up in her behavior, as well as in her ability to focus on schoolwork.
Another thing that changes this time of year is holidays- time off school etc. Even though the holidays haven't officially hit, school work, school lessons, etc may be changing due to the upcoming holidays. For instance, our schools often have concerts or plays before the winter break. In early elementary there was almost always some type of class lesson that was "big" in that it involved costumes or food or parents getting invited to a class party etc right before Thanskgiving (and again before the winter break). The weather is colder, so kids are having to bring bigger coats, maybe snow pants to school, having more to do to get dressed to go out to recess. Even things that seem small to us as adults might impact the dynamics of a classroom in a way that seems big to a kindergarten student.
I also wanted to mention one thing about SAD for anyone who's reading this and wondering if it might be impacting their children - my EG ds with the expressive language disorder is old enough now that he is able to think a lot about when and why he's sometimes able to write really well (words flow effortlessly) and other times he can't get a thought out of his head, and he's made the connection that the ups and downs are often related to the amount of light he's in. It's not so much seasonal with him as what's happening on that day - is it cloudy outside or is the sun shining brightly? Has he been sitting at a table in a semi-dark room trying to work or in a very bright area? As the days get shorter, it significantly impacts the amount of light inside our house due to outside being dark before we arrive home - so like someone else posted above, we've given our ds the option of staying at school in his school's after-care program so that he can finish his homework at that same time of day he'd usually be driving home - just that difference of not driving home in the dark has made a tremendous difference in his ability to complete his homework quickly and easily. Being around other kids also helps him - that's just his personality, he's a bit of an extrovert. FWIW, he's not actually interacting with the other kids much or goofing off - the adult in charge always tells me he's the one kid that comes in, gets his books out and spends the entire time working on his homework until he's done. But being in the same room with other kids keeps him perky.
moomin, I hope you're able to figure out what's up and find ways to help your dd settle back in happily at school -
polarbear
