For me, afterpains felt a lot like early labour or really bad PMS. OOOUUUUCCCCHHHH. Not fun when trying to relax and nurse. I think they typically last 3-5 days post-partum The pain you are feeling is probably more related to your tear/episiotomy. It might take a while before that feels OK again. If it is really bothering you, or if you have a smelly discharge, or if you develop a fever, make sure you let your MD know! Maybe mention this feeling to your doctor at your 6 week appointment anyways, just so that he/she can make sure all is healing the way it should.
All the best!