Clogged duct that will not go

I have a small, but quite painful lump right by my nipple, I’ve called my health visitor and she thinks it’s a clogged duct. I’ve never experienced this before. Because it’s right by nipple I can’t massage it while feeding as it’s in baby’s mouth, which is sore but not incredibly painful. I’ve tried to express but again due to it being right by my nipple it’s blocking the milk coming out and I’m expressing less than half an oz, It doesn’t even fully cover the bottom of the bottle, when I can usually easily get 3-4. I don’t want to stop breastfeeding and I don’t want to get mastitus, (obviously, who does, I know.) but I’ve tried everything and it’s not working. Hot shower, hot bath, expressing, feeding, massaging, combing but nothing is working and I’m getting really quite upset about it.