Gout can strike if the uric acid level goes noticeably up or DOWN.
Assuming you had UA crystals in the joint (which could have formed there because you had high levels of UA for a long time), when your blood UA level dropped (because of the measures you took) then the body tries to balance the UA level (isn't the human body clever?) by dissolving some of of those crystals to make up for the lost UA level. (Normally, when you are not having a gout attack, these crystals are covered up with some kind of protein and your immune system does not "see" them.) So, in your case, before dissolving these crystals, the body has to "uncover" the crystals by first remove some of that protein. Once the crystals are "visible," the immune system sends antibodies to isolate these foreign objects. That causes inflammation, swelling and eventual pain. This should last until either the crystals dissolve and/or the remaining crystals get covered up with protein again.
Kind of a vicious circle: the body does not like it when crystals are formed nor when they are dissolved.
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