I just changed my exclusivly breastfed 4.5 month ds and there was a solid lump in his diaper. This is the second, possibly the third time this has happened in the last few days. What is going on? Aren't his bw supposed to be kinda liquidy? He has had some problems where he hasn't gone very often and then they were very thick, but this was a big lump. It was the size of 2 or 3 grapes. IS this normal?