You can try doing some tricks to help him ease into sleep. You have to teach babies how to sleep and help them along.
1. Lovey, some type of lovey and it doesnt matter what it is, so long as you feel safe with him sleeping with it. I use a knitt blanket that has larger holes in it, even if it did cover her face she can see through it, and breath fine.
Take the lovey and start getting your scent on it, place it between you and him while he nurses, then give it to him ONLY for naps and bedtime. It stays in the crib unless it is with you when nursing.
The lovey after a little while become a sleep aid and a cue to him that it is time to fall asleep.
2. Second sleep cue, I like soft music, same CD every night and it is her cue it is sleep time. If she wakes in the middle of the night I just turn it on and walk awy.
3. Tanking up, just what it sounds like, you tank him up with food before bed. Nurse him every hour before bed for 3 hours. 5:30, 6:30 and 7:30, since he is 6 months old you can try adding in some veggie around 5pm. If you do a mix of bottle fed and nursing I would stick with whatever you do now right before bed, so if that is the 4oz bottle then keep that but nurse him twice before.
It is a personal call here, but if you dont think he needs the food at 3am then I wouldnt give it to him. I do not pick them up in the middle of the night (once they can and do sleep through the night and they wake up sick or with a night terror then yes I do, but I didnt while helping my daughter learn to sleep)
I will go in and turn the music back on, give her back her lovey and tell her I love her. If she was overly upset then I would stay with her for a little bit and just sit there or sometimes place my hand on her back/belly. I did not pick her up. If you think he needs food at 3am, I would pick him up nurse in the dark room, would not talk with him, and put him right back down, with lovey and music.
It takes a few nights (can take a week or more) but they learn that they do not get to come out of the crib at night, they learn the pattern and become comfortable in the pattern. Right now the pattern he knows and understands is one where he gets up twice and then gets to sleep in a different bed. That isnt bad that is just his current pattern and you can change it if you want.
If you help them learn to sleep with special cues then it makes life so much easier. No fighting to go to bed when they are older, you can take a trip anywhere you want because when it is bedtime you hand them their blanket and turn on the music and they are out like a light.
Its all about teaching healthy sleep habits. I am not a person who lets my child cry it out, but I dont consider them crying in their crib with me sitting there next to them crying it out.