JKC,
Mood swings are DEFINITELY a symptom of PCOS. Before I started treatment, I had major mood swings - they were so bad that I could even tell that I was overreacting over little things (but of course, who wants to admit they are wrong at the time?). Since PCOS is a hormonal imbalance, and we women get a lot of our emotional reactions as a product of our hormones, until your wife's PCOS (or hormones) are balanced or regulated, her mood swings could continue to be exaggerated.
Here are a few things I would suggest to encourage your wife (I am a wife myself):
1. If you haven't found a new doctor since you moved, suggest that your wife search for a doctor so that you can BOTH have a physical and get comfortable with a new doc. (I know that may be a big step since you don't like doctors, but this is one way to send the message that you're concerned for her without being pushy. Also, showing concern for her by stepping out of your comfort zone will help her feel more supported - it's like you're going the extra mile.)
2. Nobody is perfect, so do not begin beating yourself up for her mood swings. (You won't be able to be helpful and supportive if you put yourself into a depression.) You are more than capable of analyzing a situation and coming up with a logical conclusion as to whether your wife's words and actions are purely emotional or based on factual events. If, after examining a situation, you (or she) did something wrong, then of course, work out the problem with her. If, however, you can come up with no logical reason she should be angry, upset, etc, then wait for her to calm down. When she is calm, always be sure to ask her whether there is something you can do to prevent having the same fight or disagreement again. This will show her that you care about your relationship, and also will help her to realize when she is overreacting, without you actually saying the words "you are overreacting." (Do not be afraid that this will start her off again; even if it does the first time, your continued concern will not go unnoticed.)
3. Take walks, go swimming, or join some kind of sports league together. Increasing activity levels is one way that every doctor suggests to help treat PCOS symptoms. (In fact, my symptoms are fully controlled by diet & exercise.) You being more conscious of exercising regularly will make HER more conscious of it. And, if you are doing the exercising, too, then there will be no "are you trying to say I'm fat?" thoughts going through her head. (Sorry we are such complicated creatures.

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4. Help her cut out junk food by cutting junk food out of your own diet (at least when she's around). As I mentioned, some control can be gained with diet & exercise alone, so replacing junk food with fruits & veggies can help immensely. (Just don't do this so drastically that you find yourself ripping a candy bar out of her hand and replacing it with a banana - that wouldn't be nice.

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5. If you are worried at all about your marriage, see a marriage counselor, pastor, or someone else qualified to discuss any issues you are having. Even if you think some of your issues could more easily be dealt with if your wife was treating her PCOS properly, talking to a third party could be a step to helping her realize that, too. There is also the possibility that you are wrong about that, and your issues would be just as crummy with her PCOS under control. My genuine advice is don't take a chance. Take care of your marriage.
Sorry my advice is so lengthy, but hopefully it will help!