diverticulitis and miralax?

I am 63 yrs. old, and have diverticulitis, and am on my third day of Moxiflaxin, because I can't tolerate Cipro and Flagyl. Because I have severe chronic constipation, I take Miralax (PEG) daily.  The emergency room doctor that dxed me (with CT scan) advised I be on clear fluids for a few days, and advised me that perhaps Miralax might not be such a good idea until flare-up over. I am still on clear fluids but I feel constipated now and wonder whether Miralax with diverticulitis that isn't totally resolved is advisable, and if not, what should I do? Can't reach my family doc or my gastroenterologist (I'm in Canada).
Thank you.