Thank you for the info. I went today back to the place where they took my tooth out (it's a university hospital) and what they did was x ray to see if there is any root left and was none. They put some local anaesthetic and cleaned the socket very well and then they closed it with stitches very well. They also gave me antibiotics for the infection and some nose spray. Going back on Monday to have something fitted in my out (they took measure today) that will protect the socket from anything going in there. I already feel a bit better, except the uncomfortable feeling after the stitches and a bit of coughing. I can update with my progress, but I will definitely think twice next time if I need an extraction again.