How can you tell if food actually disagrees with your baby? Sorry but mentions poo again!

[Sistermoondance]

I know that probably sounds likea ridiculous question... But I have found that since beginning weaning my DD (started 3 weeks ago) her poos are so different ranging from normal yellow runny breastmilk ones to green fairly solid ones. And last night it was very liquid and looked like snot! Sorry if TMI. DD seems pretty happy in herself- but lasts nights nappy was awful. Made me wonder if I had given her something which disagreed with her!

Any advice?

My DS had exactly the same when we started weaning but it didn't seem to be consistent with any one food so I chalked it up to his digestive system getting a bit of a kickstart. Now, 5 weeks into weaning, he's back to normal, and the quantity has cut right down too (we had 7 in one day at one point!)