Tumor growth during chemo

I was initially diagnosed as stage 3. After surgery and chemo, I went for scans to prepare for radiation - and a new tumor was found in a sub clavicle node. This was not on original scans . I was reclassified to stage 4, although the BC nurse said that it was borderline, as some onc view subclavicle as a distant metastasis and others don’t - but my insurance company accepted this at review. My onc who was amazing, said that this indicated the chemo didn’t work as there should be no change during treatment and this was not apparent in per treatment scans- a 1 in a thousand occrence She felt that this was a really serious setback. I then emigrated to a different continent. 7 years later I still have 6 monthly scans. But my onc here, whom I also think is amazing, stated that while my treatment was exactly what he would have indicated he is certain that the sub clavicle node was present prior to starting chemo and was missed. I truly don’t know if I am stage : or stage 4 and while it shouldn’t matter - I’d love to know what I’m up against. Has anyone else a) had a sub clavicle met NOT classified as stage 4 and b) had a new tumor during chemo ( note that radiation blasted it to smithereens!