High ammonia levels may suggests she has a liver
Is she is still constipated worthwhile getting a per rectal finger examination done to look for impacted stools, if they are there need to be manually evacuated aided with enemas and other stool softners like liquid paraffin
and other purgatives as per the doctors advice.
Also ensure she is not on medications causing constipation
(some pain killers) and gets adequate hydration and fiber in diet.
Hope this answers your query.
Wish her a speedy recovery.