Fussy while nursing

Has anyone else's LO suddenly become fussy while nursing? My LO is 15 weeks and for the past 4-5 days has gotten extremely fussy at the breast. He latches on and off, cries, and repeats. When he first starts nursing he will do great for about 5 min. Before this he would nurse about 10 min on each breast. He is EBF but I broke over earlier and gave him a bottle of BM. He drunk 6 ounces. I have cried. I'm not sure what is going on. 😞