It's good to be concerned, but in general, if you can move a lump around in your breast, it's probably a cyst, not a tumor. That said, have it checked out - ANY new lumps in your breast that don't come and go in synch with your menstrual cycle should be checked out. - PJH

When I found my lump back in 2005, it was after I miscarried my 4th pregnancy, this one at 14 weeks.  I found the lump a few weeks after a D&C and my breast were returning to "normal" (since pregnancy can cause then to be hard".

You could grab my lump between your thumb and  forefinger and it did move just a bit, not drastically.  When you grabbed it it felt like a marble and I swore I would NEVER forget "that" feeling again.

Everyone is different.  Even when I had found a Cyst in my breast it moved slightly, before it finally disappeared!

Your best bet is to get a mammo and ultrsound, one will detect if it has that cancerous appearance, the other helps to determine if it is fluid filled or solid.  From there you head for a biopsy or lumpectomy - but don't worry about that now.  Peace of mind is one of the most important things, so run it by your doctor just so you can sleep easy.

Hope that helps, and that the results are clean!