Are your nipples healing now, or do you still have pain while nursing? I am asking this because if you are still in pain, it is possible your latch is not OK and needs to be corrected. If you suspect this to be the case, let me know, we will help.
As for a sleepy baby... We tried nursing our dd in diaper only so she wouldn't get too cozy soon, massaging her neck, or patting her hands. Some keep their little ones awake by rubbing their face with a wet washcloth, I never tried this. However, at this age it is sooo normal that they fall asleep on the job. Try this and see if it works but soon, he will be less sleepy and more alert, he will become more efficient nurser and if you keep EASY cycle he won't fall asleep while nursing. My dd started to be super fast nurser at around 7 weeks, she was usually finished in 5 minutes.
Good luck!