I was REALLY bad after I had Harry.
I had a 2nd degree tear and a MASSIVE bruise on my bum (for some reason!) The midwives said it was caused by the pushing stage! It was the size of my whole hand, was completely black and was so painful I couldn't stand (or sit) and had to just lie down and not move for it not to hurt. I was on painkillers for a fortnight, and it finally went after a month.
The 2nd degree tear didn't cause me too much pain - it was just uncomfortable and would sting when I went to the toilet which I think is quite common.
As for back ache - I didn't have any immediately after the birth, but certainly have it now! I've also now got incredibly bad ankles and my pelvis is painful too. I had SPD whilst pregnant which has gone, but is aggrevated by my long walks with the pram each day. I'm putting the back and ankle pain down to going from doing nothing whilst pregnant, to now lugging Harry around and being really busy and mobile.
Hope you feel better soon.