I agree with WC - especially the bit about BOTH of you getting checked over - that's a brilliant idea. I mean, it's a good idea in and of itself, we should all keep up to date with our check ups and 500,000 mile services and what-knot

But it also a great way of you saying this to her without sounding like you are having a go at her.
I know it is very difficult to gauge her moods, changeable as they are, but if you can try to catch her on an up to have this conversation you'd be doing both of you a big favour.
Try to be a little careful with your language - make sure you don't use too many 'you are X' and 'you should Y' type comments - she will feel attacked. We know you're not attacking her, but that's not the point, if she feels attacked I expect the conversation will end or, worse still, deteriorate pretty quickly. Try lots of neutral language - '
we need to...', 'wouldn't if be great if
we...'. Try to use 'I'd like' instead of 'I want' and even 'wouldn't you like...?' instead of either. Stuff like 'I think X, what do you think?'. Make sure she can tell it is about her being happy - not about you. Because, let's face it, you are only going to get respite from your current situation by leaving it (which you don't want to do, from the sound of it) or by helping her be happy and comfortable.
She does, I believe, owe it to herself and you to recognise that there is a change going on and that it needs to be better managed than it is currently. The problem you face is getting her to see that and act on it while these hormonal mood swings are, at least in part, controlling her actions and reactions.
Best of luck with it - the prize is worth the fight