Help! Infant stringy lime green stool

Hi! FTM here to a 5 week old. I am exclusively breastfeeding. He’s never had bright, seedy yellow poops but they’ve at least been orangish/brownish with an occasional green poo.

This past week however, they’ve only been green. They started out dark green and now are bright, lime green. He just started having stringy brownish mucus things in his stool too.

He’s never had trouble breastfeeding, typically has a good latch, feeds 7-8 times a day, produces 6-8 wet diapers, and 4-5 green poos. I typically block feed to try and increase his chances of getting hindmilk. He has bad reflux but isn’t in any medications.

What am I doing wrong? Is this normal, or does he have an allergy to something I’m eating?