Either it's leaking and you miss it dripping while driving or it's burning it! Do a cooling system pressure test and locate the leak. Intake manifolds and water pumps are my first areas of concern.
may be u fried the head gaskit and ur coolent is mixing with engine oil.thats very dangerous for engine. open ur oil cap/take out dip stick and see if it shows any syrup type brown colored liquid.if it does, certainly the oil and water are mixing.