Those symptoms could only be caused by two things: an uncomfortable fit or the noise-cancelling technology itself.
The Bose QC15 is one of the most comfortable headphones ever made, in spite of being an older model, so I doubt it’s a fit problem. But to check, does this also happen when you just wear the headphones with them turned off and nothing playing?
If so, then it’s the active noise-cancelling. And I’ve got bad news for you…switching to a different headphone probably won’t solve the problem, as they all use similar underlying technology. Every ANC headphone works by generating anti-noise based on the sound of your ambient environment, and pumps that into your ears. This causes some mild pressure on your ear drums, which should be a little easier-feeling with music playing.
Some folks report discomfort in their inner ears/eardrums from this experience, and it’s supposed to diminish over time if you can get used to it. That discomfort can indeed cause mild headaches and nausea, as our inner ears are complicated places responsible for all sorts of sensations. If you’ve given yourself some time to adjust and it still hasn’t gone away, then a different headphone won’t help.
I’m sorry this isn’t a very optimistic response! Thank you though very much for reading and taking the time to write a question.