Its been 6 days since my wisdom tooth surgery. is it normal for my bottom second molar to feel sore and loose? and why?

Sounds normal: Disruption and swelling in the area from the surgery would make the area sore for a week or two. Also it will take months for the bone to heal and fill in, so the loosening of the second molar is also considered normal at this time, again, due to the trauma of the surgery. For further info on your particular case, the doctor who performed the surgery is your best reference source.

Possibly: It is possible that during the extraction of your 3rd molars, the 2nd molar was "pushed" on or "leaned" on to help the dentist remove the tooth. Also, because of the work done in the area there can be soreness throughout the entire jaw including the teeth in front of the 3rd molar. Certainly check with your treating dentist if you have a concern.