What Causes Yellowish Discharge After Having Hemorrhoids Surgery?

I am 68 years of age, male in fairly good health. On 24/2 I went to the hospital for advice about hemorrhoids and was immediately admitted and operated upon. Since discharge from hospital (I was in for 3 days) the swelling, pain and blood have reduced considerably but I am still getting a yellow (none smelling) discharge in my pants. The surgeon has recommended limited walking or exercise, which is almost impossible.