We had a similar experience with our son when he was an infant. I would try to nurse, that wouldn't work. My husband would rock him, that wouldn't work. Finally around 4 months old, we realized that we had to go with our last resort - letting him cry. He was old enough at that point where he didn't actually NEED a feeding in the middle of the night, so we felt OK about that piece, but felt awful about letting him cry.
We gave ourselves a time limit for how long we'd let him cry. I think it was 30 minutes. The first night, he cried that long and we brought him to bed with us. The second night, he cried only 17 minutes. It took only 3 or 4o nights before he stopped waking up entirely.
Mind you, it was awful - it's 2 1/2 years later and I still rememberthe exact number of minutes he cried that 2nd night! It honestly was our very last resort. We never thought we'd let our child cry, but during the 2nd night, we heard him soothe himself by sucking his thumb for the very first time. Now he still sucks his thumb, which we love because he has a built in soothing mechanism.
Most important part of this process was for my husband and I to agree to a time limit before we went to bed. That way, we weren't half asleep arguing about when to go in.
I hope that helps - good luck!