I was driving on a very busy highway going about 20 km/h - 30 km/hr. There were multiple trucks carrying construction equipment/vehicles on the highway. I was switching into the right lane when the car beside me switched out of that lane, when i heard a slight screech behind me. I thought it may have been the sound of a truck, but also wondered if i had hit the car behind me, since they were following very close. The car did not honk or try to signal me down, so i thought it most probably would have been truck noises. We were almost in stand still traffic so they were following behind me for a while, until several cars switched lanes behind me. Im not sure if I had hit the car, and unsure about what to do. The other car was fairly old, and again the driver did not try flagging me down. The back of my car has a scratch/crack, but im not sure if that was from a previous accident. Please help? What should i do?