What Causes Excessive Thirst And Sweating?

I'm 28 (female), normal weight and I break out in sweats and get very thirsty when I eat sweet things and refined carbs. I've got a history of low blood pressure and sometimes low blood suger. The thirst can last for a day or two and the sweats for about an hour after eating sweet things. I am often tired and get shaky. Any idea what this might be?