My son loved the "MAM" brand bottles/nipples.
I got it from Amazon.
It is also BPA free.
Not expensive.
Even comes in 3 packs. And is cute!
I loved these bottles and so did my son.
It also does not accumulate air bubbles in the bottle as the baby drinks.
It is also used for colicky babies.
Your son is probably spitting up because the flow is too fast. Also remember that he is only 5 days old... they don't drink 3 ounces at a time.
And per nursing, a baby will drink until they are full, AND your breasts and its output will adjust TO your baby's intake. Thus, nurse on demand.
On the other hand, yes, you need to check with the Breastfeeding Consultant.. because he may not be latching on correctly. It should not hurt, when he latches or nurses.
Use breast cream, lanolin as the other poster said.
My son would take breast or bottle. However, the more he got a bottle, the more he didn't want breast. Because bottle was easier to suckle from. It being only by gravity.
So just a head's up. Some babies may start to prefer one or the other.
Also, when showering, do NOT "rub" your nipples nor with soap. It will dry the skin up and hurt more.
Just rinse it, with water.