You just stick a sterile needle in her to let the fluid out, if you have one; you can get them at the feed store. If you don't have one it's pretty hard to come up with a substitute as it's both sterile and hollow. This might relieve some of her discomfort but would not cure her.
I'm afraid there is probably not much you can do for her but keep her comfortable, anyway. Sorry to say that. I'm afraid that whatever is going on in there probably couldn't be fixed, even by a vet.
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It might be time to think about ending her suffering. If you can't do that, or don't want to, there is nothing wrong with that. I'd put her in my bathtub wrapped in a bath towel, or some similar arrangement, where she'd be warm and as comfortable as I could make her.