It could be teething, perhaps the upper or lower molars? I'm a HUGE fan of Orajel nighttime relief along with infant Tylenol. Our daughter had 8 teeth by 6 1/2 mos (4 top / 4 bottom) and had 12 teeth by 11 mos. Do you have music playing for him or white noise when you put him down for the night? Either of those things could help soothe him. I've put together half a dozen mixed CD's for our daughter and she seems to enjoy them. The 80 min. recordable CD's are great, 'cuz that's an hour and 20 minutes for her to fall asleep to!
I feel you on the sleepness nights, just tell yourself that it won't last forever. Easier said than done, I know. Lord bless you for dealing with this SO well since you're working full-time. Your co-workers and boss should thank you for all that you do!