Hello and welcome to HCM,
Thank you for your query.
It appears to be that your partner was suffering from constipation
all these days. More recently, after being advised medication from a doctor, he is noticing the presence of mucus in his stools. The possibilities could be many, but here is a short list with the most common ones:
-Irritable bowel syndrome: Ulcerative colitis
or Crohn's disease
-Inflammatory bowel syndrome
Although stool normally does contain a whitish jelly like substance that helps in lubricating the colon
, but if this has been observed more times than usual, then a re-visit to your doctor would be necessary. Also, avoiding straining during a bowel movement is advised.
I hope I have succeeded in answering your questions, you could write back to me anytime for further clarifications.