I think I have a dehydration problem, not sure what's caused it.

I've been drinking loads of water, no additional beverages except a cup of green tea here and there. I've felt fine all along, ketostix light pink. Then Suddenly:

Last night I made spaghetti squash with sausages (locally Mennonite made, no fillers), mushrooms, parmesian cheese, spices. When I was done I felt so bloated I thought there must be something wrong with the sausages, but no one else had any trouble with them. Then I thought perhaps I had overdone the squash (only had 1/2 cup) and ended up with too much carbs. Took a quick check of the ketostix and they were so dark they were almost black, never been that dark before. Woke up with a splitting headache this morning and my tongue stuck to the roof of my mouth.

Nothing I haven't eaten before, drank my whole gallon of water yesterday, eggs for bkfst, lamb, salad, cheese for lunch. Does anyone know of any other causes of dehydration? Assuming that's the problem, of course. Could it be something else? Can someone develop a sudden reaction to something like mushrooms or squash?