Hi Shroom! Sorry to hear you're feeling funny - i just wanted to compare notes on one of your symptoms. I have chronic insomnia, one of my major yeast related problems. I'm kept awake by a combination of feeling "racey" and by a pain, it feels like a clenched fist, under my left ribcage by my spleen. It just sounds so much like what you're experiencing. I really think you're just herxing, but if it keeps up it may pay to get it checked out. I think, but I'm not sure, that this pain is a kind of lymph problem. There are major lymph-nodes near the spleen. Perhaps the lymph system is just overloaded with toxins or something?
anyway, i'm not gonna spout advice as I have no clue - but I just recently noticed that my spleen pain, which I've had for 15 years - will actually go away for a few hours if I get a really strong massage. That's why I recently started thinking it was lymphatic in nature. But I dunno - just sharing observations.
also, my intuition tells me that no probiotic can really overgrow to dangerous levels... but I don't know. hope you feel better soon and keep us posted on your progress.