Thank you for your query,
In a 9 week old infant constipation
Infants will make sounds or do strain at the time of passing stool and it is not due to constipation but for a effort to pass the stool.
The mucus and the watery stool may be a response to the suppository insertion in the rectum
So avoid frequent insertion of suppositories by thinking it is constipation.
Hope i have answered your query.