Lesley - I haven't seen this problem with a baby, but my sisters 3 year old has had terrible problems with her bowel. Nothing that has caused a hernia, but she has required several enemas as she doesn't like to poo, so she holds on and it makes it harder and harder until it hurts too much to push out.
Anyway - she had to do the laxative option, and it did help, but the only problem was my niece was popping out tiny little poos in her knickers al the time.
She was really hard to toilet train in general, but thats not to do with any problems as a baby.
I hope Chloe will be fine, but I just wanted to let you know that my sister had to use a baby laxative too, and it worked really really well at softening her poos. I hope that helps.
Fi