This is a question for the surgeon that performed the sinus lift. PLEASE make an appointment IMMEDIATELY to see your surgeon, the ongoing congestion may be a matter for serious concern.. If for any reason you are not satisfied or unsure about his/her evaluation seek a second opinion from a qualified dental surgeon or ENT doctor.
You should be receiving ongoing observations during the healing period. I generally see my patients to monitor healing at 2, 4, 8 and 16 weeks, more frequently if necessary. If there are any signs or symptoms they are dealt with accordingly.
Dr David Azar