Hi love, from my limited experience you can tell by the size of the poops, they're smaller, and then you notice that they having a few problems.......then when you pick them up their little bottoms are quite swollen
You need to be careful and extract them carefully, it's not pleasant but it's such a relief for them!
Usually it's in older piggies, but i think i remember someone elses piggie had problems after his 'operation' and was a bit impacted :{
If you do a search you will find there's been some previous cases, would be interesting for you to read them
Hope the boys don't become impacted, all paws crossed here xx>>>xx>>>xx>>>xx>>>