If you have a little one who is hitting a growth spurt and getting breastmilk, I'm not surprised that he's fussing at night.
It could be a few things: breastmilk only 'lasts' for about four hours in the stomach. If he's ramping up to grow, he'll need more milk/food. If your little guy likes avocado, I'd try that before bedtime, as it is a fat and might stay with him a little longer. Or some rice cereal mixed with breastmilk, or rice mixed with some babyfood veggies. (the sugars in the fruit might digest faster-- I am not sure of this, however.)
He might also be 'practicing' his crawling, even in his sleep. This could wake him up. Kids do this sometimes when they are trying to master a new skill. One 6 month old recently in my care was napping pretty well until she started crawling-- I was lucky to get her down for 20 minutes at a time, even with a full stomach. I also thought she might have been teething too-- they seem to go together, sometimes.
Lastly-- any drooling, hand in mouth, sore gums/teething sort of symptoms? My son (and many kids I cared for) were super-fussy and needy when their teeth were moving around, even before they erupted. Those little teeth are still having to come up through all that tissue. Nursing and Tylenol were my saving graces during these times.
I can't suggest CIO-- I hated doing it as a nanny and never did it with my own son. (He sleeps fine, btw. No permanent bad habits.) That said, maybe one of the above will ring a bell for you. Sounds like you are taking care of it