The increased emissions light has also just came on.
What caused My BMW 530i to just start running rough and smoking? on 2004 BMW 530i
It could be many things, unfortunately and without experiencing the problem first hand or being able to do some basic diagnostic tests its hard to say. It could be too much fuel getting into the engine causing black smoke to come out the exhaust. White smoke and overheating could be a blown head gasket. If the engine has a damaged oil rings or piston damage then the spark plug may foul and run poorly.