I've had every breastfeeding problem under the sun, and I am still breastfeeding.
I've had cracked nipples, oversupply, overactive letdown, under supply, mastitis, blocked ducts, vasospasms, latch problems, dairy allergy issues with both myself and Lucian.
Cracked nipples - caused by my son's shallow latch. Was corrected by a lactation consultant while in hospital.
Oversupply - have no idea what caused this, but oversupply is quite common for the first couple of months
Vasospasms - something that you cannot avoid if you get them.
Mastitis - first time, caused by a combo of cracked nipples, exhaustion, and a infection in my c-section scar
At the moment, I am on domperidone (luckily I am now down to two tablets a day), after I got infective mastitis for a second time, along with a nasty cold and food poisoning. It really hit my supply hard. I tried every natural remedy, but at the end I had to resort to domperidone.
I also see a lactation consultant on a regular basis, who has helped me immensly with all of my breastfeeding problems. It has been worth the money.
Here is a link to a list of certified and registered lactation consultants in the BOP:
http://www.nzlca.org.nz/search/bayofplenty.html