Regarding bras:

If you had your boobs made, they're probably pretty close to the exact location and proportions that bra makers expect. But if your boobs are broad rather than projecting; or set closer or further apart than the typical bra in your size... underwire pokes in all the wrong places. (Don't get me started on all the assumptions built into women's clothing and bra sizing.)

Plus if you've got an extra layer of fat on your torso or wear it too tight, the band can dig into your skin. If your band is too loose and you have big boobs, the weight falls onto the straps and hurts your shoulders.

That said, a lot of women who find their bras painful are wearing the wrong size.