2000 Jeep Grand Cherokee Coolant Leak?

For about 2 years, the Coolant Low light has been coming on every 2 months or so, at which time I would just refill the coolant. However, in the past couple days, I can fill the reservoir to the top and have it be completely empty after 50 miles or so. When I park the car, I notice a steady stream of coolant leaking onto the groung from under the very front of the car. Also, in the last 2 days or so, the engine has been running a little rough, presumably because it's not getting any coolant. The gauge inside shows it running slightly hotter than normal, but it hasn't over heated or anything. Also, occasionally I can hear what sounds like a swishing sound when I first accellerate after starting the car. The oil is normal in color and the reservoir doesn't appear to have any oil in it. I'm a 23 year old idiot when it comes to cars, and I'm trying to cover my brother's medical bills so I really can't afford to do much. Please let me know what you think the problem might be. Thanks