Sounds like a blown head gasket! The heads may be damaged or cracked and you might have bent some valves! If you have automotive experience, you can pull the heads and have them checked! If not, you'll need to get it to a Certified mechanic to check out and give you a price for repairs.
Most likely your head gasket is blown, or the head is cracked or in a worst case scenario, or both. Depending on the mileage, you can be able to get by with a replacement head gasket. You may also have to rebuild the whole engine.