HI J.,
Congratulations on the birth of your son. I'm sorry you are experiencing the pain when you're nursing. Contrary to what we are told, we shouldn't be experiencing any pain when nursing. With a clogged milk duct or mastitis you would have pain in your breast and the area would be tender to touch, red or hot. Are you experiencing any of those symptoms on top of the stinging?
I would gather from the information you provide that you may be experiencing the discomfort from an improper latch or possibly thrush. I recommend that you start with your local La Leche League and consult with the leader prior to seeking breastfeeding advice from your doctor. I've encountered many women that have been misguided by their doctors, due to lack of information and education when it comes to breastfeeding.
Here is the link for your local La Leche League. http://www.lllofnc.org/Groups/charlottearea.html You should be able to get accurate information and breastfeeding support to determine whether this is solely a latch issue or something that you would need to seek medical care.
I would also encourage you to nurse from each breast. Breastfeeding is a supply and demand. If your lo is nursing more from the right than the left, the right breast will be producing more milk(which may be why he's nursing better from the right). I would suggest changing the nursing position or how you hold your lo while he's nursing. This may give you some relief while you troubleshoot.
Here's another link for breastfeeding support and advice from Kellymom. http://www.kellymom.com/
If you are dealing with thrush, I've copied and pasted this information from a post I responded to here a few months back. I want to point out that you have other options besides antibiotics and you will have to be diligent with most of these suggestions or you'll create a vicious cycle. I never experienced thrush but I know it can be very troublesome at trying to eliminate. I think you'll find this link and the suggestions offered helpful.
http://www.breastfeedingonline.com/yeast.shtml
NO SUGAR of ANY kind, you may need to avoid fruit for a short while. Your diet is absolutely essential if you're going to beat yeast.
Grapefruit seed extract 250 mg 3 or 4 times a day.
Coconut oil has anti fungal properties and can be used topically and ingested.
Start taking probiotics and giving them to your baby too.
Eat yogurt...no sweetened or fruit added ones.
Purchase some Gentian Violet to treat yourself and baby.(This turns everything purple)
Use a cup of vinegar in all wash loads, particularly towels, nursing bras and baby's diapers.
Sterilize any pacifiers, bottle nipples, nipple shield and pump parts daily and wash them in a vinegar solution or paint them with Gentian Violet.
Echinacea and Astragulus Root, and Vit C and B-complex vit. to boost immune function.
Congrats again on your lo and may you find the support you need for continued success in your nursing relationship.
Peace,
J. Lenz