Arvi could it be his teeth? moving or coming through.
The fact that he is waking crying could be pain - its more noticeable at night (for babies that's true too). And he could be breastfeeding more to sooth his gums. Try some pain relief and see if it stops then you know. Or he's calling out to you - separation anxiety may also have started for him. We've seen both and if its not teething pain then baby pain relievers wont stop the crying so then you can try strategies for the anxiety.
Our little boy has never been a wonderful sleeper - have read so many sleep books and tried so many things and we seem to take two steps forward and one back.
For us Dr Sears, Pinky McKay and Elizabeth Pantley's books are favourites - realistic and gentle and they know what they're talking about - all big researchers into child development.Be warned of sleep trainers and leaving baby to cry alone (or protest until they become distressed) - let them grizzle a bit and protest sure but if they are getting upset then step in quickly - if its separation anxiety leaving him wont help.
We recently tried to help our baby boy learn to "self settle" in his cot alone (he has turned one so we thought time to try again) and after three days of this he now screams if he's taken near his cot or we turn on the mobile. So for us its back to bouncing him to sleep on the exercise ball with lots of cuddles to heal from the trauma

one day he'll get it.
Let us know what works