Pearl had no problems until around 18 months old, then persistent anal gland infections that resulted in them being removed, very successfully. There is a thread on here about it.
Pearl has always had very small, hard stools even when fed kibble. She's been on raw food for the best part of 5 years now and although it helped with the gland issue it was never going to cure her problem. Following removal, the Vet told me they were 3 x expected size!
Diet can help and certainly a raw carrot each day plus bran sprinkled on each meal helped a little.
Hope it's a passing phase for Charlie