5wks post hemorroidectomy.today i was constipated and took miralax (polyethylene glycol). stool hard painful to pass & bright bloody mucus when i wiped. should i go to er?

Keep stool soft: No, but i would take MiraLAX (polyethylene glycol) or some gentle laxative on a daily basis, and keep your self well hydrated. Also consider adding some fiber like a 'metamucil' or equivalent once a day to keep your bms soft and regular. If this happens and the bleeding continues, then you will need to have it checked out. A hemorrhoidectomy takes a while to get over.