My six-month-old has suddenly lost interest in breastfeeding and is not latching like before? What do I do?

My baby isn't breastfed but like what Evelyn said, yours could be on a milkstrike. It happened to my son to a few weeks back. He usually drinks 180ml every 3 to 4 hours, but he was only drinking 60ml to 80ml before throwing his bottle away. He'll scream if I try to make him drink anymore. But I noticed that ever sinc then, he's been gnawing on his toys and blanket more often so it could be that his teething. And like Evelyn mention, it's just a phase :) My son is now back to 180ml and sometimes still wants his food right after.