Hello girls. I'm really struggling. My youngest is 3 and a half months…

Hello girls. I'm really struggling. My youngest is 3 and a half months old, and he's been fussy for over a month now when he takes the breast. That means about 5 minutes of calm feeding, then he starts fussing and won't take it anymore. Almost every feeding, sometimes even several times. I previously wrote about this and asked the girls if it might be a false refusal of the breast that should supposedly pass, but each time these tantrums ? are caused by what could it be? I consulted with a pediatrician, but they didn't give me a clear answer.