DS is 5 weeks and EBF. Feeding going well, gaining weight, lots of wet and dry nappies etc. He is very happy during feeds and after if upright or on me.
However he seems to be in a lot of discomfort when I lie him down to sleep after a feed. He sounds like a little gremlin, gurgling and grunting and squirming. He is not sick, other than a little posset now and again. He cries after a couple of minutes of fussing.
I always wind him properly and keep him upright for ten minutes or so. He is having infacol to help with the burps. He sleeps on his back in a Sleepyhead or Moses basket.
Any idea what this could be? Reflux? General wind? 

Any advice much appreciated. 