How bad can the consequences of bad form dead-lifting be?

i deadlifted 245lbs in class 1 time, which isn't that much, but I'm a total beginner to weights. I had the weightlifting belt on, but I did it with all my back according to my friends. They said I wouldn't be able to get up tomorrow because of sore lower back. Next day I was okay, so I tried again and did the same weight 4 times, they said I used all back again. Right after the deadlift I had pain under my lower abs on the left side. Today, I have minor pain in the bottom part of my left lat. My question is, could I have messed anything up, and how bad can the consequences be? I will choose best answer.