Baby refusing breast

My baby is only 6 days old, this is my second baby. I breastfed my first for 16 months so I’m really frustrated and confused as to what’s happening. My milk came in on day 2. He nursed fine but has since been refusing my left breast. It doesn’t get “full” anymore and I’m afraid I’m losing supply in only my left side. I try to attach him more so that it can make more milk, but he straight up refuses it. He’s bob around on it for a few mins and maybe I’ll get lucky with a 5 min feed but then after that, he loses it and no matter how much I try to help him latch, he won’t. He breaks his own suction within seconds and I don’t know what to do. He won’t even nurse with a nipple shield. I’m getting really frustrated with it and I refuse to only feed from one side our whole breastfeeding journey. I’d rather go to formula. If anyone has any advice.