Who is at fault for accident?

So I was driving in the right lane on a four lane highway. A car was stopped about 100 yards in the lane in front of me, talking to a pedestrian. I checked the lane to my left, it was clear so I signaled and moved over into the left lane. The car now in front of me, in the left lane, suddenly stopped(she was waived to a stop from the stopped car that was talking to the pedestrian). I came to a complete stop a few feet behind her then I got rear ended by a truck. We got out and waited for the police, then another accident occurred. I'm an army medic so I took care of the injured individuals(with permission for the police at my accident). I was never interviewed or asked what happened but I was given a citation for improper lane change, even though there was plenty of distance between the car to my front and truck to my rear and I used my blinker. The truck pushed me and the car in front of me 15 feet and essentially ran me over. the guy in the truck that rear ended me was late for family pictures before leaving to be a missionary.