2000 Other Alfa Romeo Models TAPPING/ KNOCKING SOUND COMING

Engine problem
2000 Other Alfa Romeo Models Engine Size unknown Two Wheel Drive Manual 139000 miles

I HAVE AN ALFA ROMEO 156 1.6. THERE IS A TAPPING /KNOCKING SOUND COMING FROM WHAT IT SOUNDS LIKE UNDERNEATH THE CAR OR THE ENGINE. I HAD THE HEAD CHANGED ABOUT 6 MONTHS AGO BECAUSE THE TIMING BELT SNAPPED. IT STARTED A FEW WEEKS AFTER THE HEAD WAS CHANGED. ITS LIKE A REALLY LOUD TAPPPING SOUND. THE CAR DRIVES PROPERLY BUT ALSO IT IS DRINKING THE OIL AND I GET A REALLY STRONG BURNING OIL SMELL COMING THROUGH THE VENTS IN THE CAR WHEN THE HEATING IS ON. THERE IS NO OIL LEAKING ON TO THE ROAD SO IT MUST BE GETTING LOST SOMEWHERE ELSE. I PUT 3 LITRES OF OIL IN THE CAR A WEEK AGO AND IT HAS ALL GONE ALREADY. ANY SUGGESTIONS TO WHAT THIS COULD BE. I DONT WANT TO SPEND A LOT OF MONEY ON THE CAR AS IT HAS ALREADY COST ME A FORTUNE. PLEASE HELP!