I Had Surgery 10 Days Ago And Got Constipated I

I had surgery 10 days ago and got constipated I think from the pain medication. Was already taking stool softener so daily and yesterday started taking miralax because I got extremely constipated and had pain trying to go. I have chills at times the last few days off an on and feel weak. Is that normal? I know some of the weakness is from surgery but wondered about the chills and if I should take the miralax daily until I have normal movements?