C.M.
Sounds like teething to me. I would give him Tylenol the next time it happens and see if it calms him down.
On another note, it could be nightmares (I think night terrors start when they are older). Or he may be waking up (kind of) and missing you.
I do not think that there is anything wrong with nursing him. If you want to stop that, I suggest patting his back or picking him up and rocking him. My son has started waking between 5 and 530 and instead of getting up, i rock him (he's 1) and he'll usually fall back asleep for an hour or more.