this happened to my son when he was 5 months old. The whole little nugget thing is bringing back memories - I ended up having to give him a suppository, and he was able to poo some of it out (larger than previous nuggets) within 20 minutes. But I knew there'd be way more than that in there, so I continued the massage and warm baths etc over the next few days, and he ended up having one more suppository the next day to move things along. Once he got the hard nuggety bits out (and there was quite a lot of it, unfortunately) the rest of it went from plasticine texture to normal consistency within a couple of days.

It is so distressing for them - I remember he hated to sit down he wanted to be held upright with no pressure whatsoever on his lower belly