Did, you ever figure out what it was? Can you please tell me? My og has s similar problem.
For a lump, on a Bichon which is a very small dog -that's big. You can't guess what it is. Only the biopsy will tell you that. Get the biopsy done as soon as you can. If it is cancer, it needs to come off as soon as possible. He might need the whole outer part of his ear removed. That will make him look a little odd, but will be worth it, to get rid of this lump, whatever it is.
It may not be cancer. My dog had a (much smaller) lump removed from her lip a few years ago. The vet thought it looked suspicious. I didn't like the look of it. Although tiny, it was hard, and dark, and felt knobbly. It turned out to be an infected hair follicle! And she was fine afterwards.