As a child who experienced severe bowel problems, can I throw out other thoughts.
Liquorice - Tesco currently have a strawberry one on offer and lots of it. A bag in one sitting for me now, leaves me confined to the bathroom. At 5 years old, this might be an option alongside the rest as might be easier to consume. Present it as sweets, there is no ulterior motive as far as DD knows.
Other suggestions include milk of magnesia, figs and apricots to snack on,
Until my problem was resolved by an operation, I had the poo nurses visiting alternating days for manual removal so your DD has my complete sympathy. Its horrible, this was a last resort for me before the operation as they were trying to avoid that.
When things start moving which I hope is soon, have baby wipes and nappy bags on hand as if on the loo a lot, things can and do get painful leading to holding, nappy cream to help with site areas, tons of praise.
Glycerine suppositories are good and help a lot but not nice going in. Is she feeling sick from constipation,
Try and phrase it as a few minutes of taking medicine to relive the sick feeling, this will help it to go away or 1 minute of "nasty" drink to help the sick feeling and probable tummy pain. Can you do that, just 1 minutes to start to feel better? You are so brave etc - have some chocolate buttons to help disperse the nasty taste, so brave.