I was three times as sick with my second pregnancy as I was with my first, and sadly there was nothing I could do to make it better except to take the medication my doctor prescribed. I was hospitalized twice for rehydration, and that was really the best thing for me--I didn't have to force myself to drink the fluids, they were just put in by IV. If your doctor really wants to send you to the hospital, you should follow your doctor's instructions. Dehydration not only endangers you, but the baby.
Hopefully as you get deeper into your second trimester, your nausea will lessen. There are lots of home remedies over the counter--mints, lemon drops, seasickness wristbands--I bought them all, and nothing worked. Some people recommend drinking and eating separately--first, eat your meal (which should consist of a carb and a fat, and should be small, like one egg on an English muffin, or raisins and peanuts, or something like that)then, a half hour later, drink your fluids, whether it be water or ginger ale (flatten it by putting in a teaspoon of sugar).
Honestly, though, very little of that worked for me. It was just a waiting game, trying to get through each day as best I could. My second pregnancy was just misery after misery, but I got through it and now I have a beautiful baby girl. So just know that this, too, shall pass, and that it's worth it. But to be honest, I will never be getting pregnant again. It was just too hard the second time, and I can't risk being sick like that with TWO kids in the house.