Burning oil smell

Need some insight here. I have the car listed above sedan (commuter car). I recently changed my oil and have been driving around with a burning oil smell in the cabin. I couldn't take the smell so I took a peek under the hood. I found a layer of oil on some parts and some burning oil residue on the exhaust manifold (don't know if i'm describing the right part). I've included two pictures to describe what is see. Both of the pictures, in my perspective, is taken on the right side of the vehicle towards the back of the engine. I did some reading and have concluded to either be rear main seal or valve cover gasket, or maybe head gasket?

First picture is of the upper portion - black metal plate and the circled bolt area is coated with a thin layer of oil.
Second picture is of the burned oil residue on the, guessing exhaust manifold?