overheating and burning fluid

[Papa Rad17]

on my way home last night I was driving, not very conservatively... when I noticed my engine temp started rising a bit. I kept it at cruse speed and just drove chill and it leveled off for a bit but then started going back up. when I noticed there was a lot of steam coming from around the coolant tank I immediately pulled over and let it cool off. once I opened it up the tank had hardly anything in it. I got a cup and starting getting some water put in, it drank 2 or 3 before it finally started filling the tank. I took it super easy on the way home and would ya know, as I started getting close it started spitting out more steam as the temp went up. at this point I slowed down even more and popped my hood to get more air flow. that helped a lot and dropped the temp a bit, but then right as I was pulling it started going back up again. I checked everything thoroughly for leaks and cant find crap. I refilled everything and check it again this morning and levels were still good, but when I got home today and checked everything the tank was about 3/4 empty. there was no signs of it coming from the overflow and still no signs of leaks which leads me to believe its eating it. it has been burning a little oil for time now to, not much though. I just have to add a drop every 700 miles or so, but it burnt though it like crazy today. I had it back up to level this morning then when I got home it was barely getting the bottom of the dip stick. any ideas where I need to start? the engine is about to roll over to 200000 miles...