Crank shaft problem


I recently had my b18a motor from my 91 teg GS rebuilt from a local machine shop in my area. I have about 1700 miles on my motor, I was driving over to my girlfriends house when I heard this weird exhaust leak sound…Like maybe a burnt up header gasket or something…so when i got to her house and turned the car off and let it cool down and everything…i turned the engine back on and the exhaust leak sound was gone, but i had a new problem, my engine was making this weird knocking sound…kind of like a spun rod bearing…so i towed the car back to my house and put it up on the ramps…dropped the oil pan and all of that good stuff to have a look at the crank and the rods and stuff…come to find out that there’s an allen set screw type of deal that came out of the crank shaft and was sitting inside my oil lamp or pump, not to sure what that is…so i have my dad turn the crank while i look at it for anymore problems, and another one of those allen set screws was loose…anyone know what the heck this is or what may have happened or went wrong???