Hi Archie
Welcome to the boards. BIG hug. Hang in there. It's always said that you need to give breastfeeding 6 weeks to settle down. It's a skill that you and he both have to learn and it will be worth it in the end.
Can I ask a few questions?
Does your baby have around 6 wet nappies in 24 hours? If the answer is yes, and you are exclusively breastfeeding, then this is a sign he is getting enough. How is his weight gain? Again, if your health professionals have no concerns then he's getting enough.
When he does get on does he have a wide gape and take in a good mouthful of breast (lots of areola not just nipple, especially areola below the nipple)?
Is his body straightish when he feeds so he doesn't have to turn his head, his shoulders and hips are in line and his head is well-supported? The best way to put him on is to first encourage a wide gape (perhaps by touching your nipple against his lips or under his nose) and when you get that gape very speedily put him on your breast (move him to you, not the breast to him).
You should feel that any discomfort goes after a couple of minutes if your nipples are sore. If your nipples remain very sore throughout the feed then that might suggest your nipple is not going far enough into his mouth as they should be bypassing his hard palate and moving onto his soft palate which doesn't 'rub'.
Sore nipples are helped a lot by a cream called Lansinoh. It's pure lanolin and safe to keep on your nipples without needing to wipe them off for a feed. It's the only cream that is officially sanctioned by various breastfeeding organisations including the LLL. It helps you keep a moist environment on your nipples which aids healing. Truthfully, if you are still in pain at 4 weeks that might suggest a latching issue. A couple of weeks of nipples settling down is not uncommon but you wouldn't still expect it at 4 weeks.
Has your doctor/ midwife ruled out the fact he might have a short frenulum (be 'tongue tied' i.e when his mouth is open does his tongue sometimes make a heart shape at the end?)?
Is this the way it has always been or have the last few days been especially tough? It could be that he is going through a growth spurt ( a frantic few days where he is feeding far more frequently to build up your milk supply).
Make sure you are drinking enough and eating well and hopefully there are people who can look after you a bit.
Lastly, have you received any other advice from a breastfeeding professional as it sounds as though it might be important you talk to someone qualified. It doesn't have to cost anything. There are numbers of free helplines on the FAQ page. The La Leche League is also a free resource with local 'leaders' who are trained counsellors. If you do suspect it might be a latching issue then it would be valuable to try and see someone face-to-face. I really would suggest you try and talk to someone IRL (in real life)! One five minute conversation could make all the difference and even if you pay for a lactation consultant it would still be cheaper than several months of formula.
Good Luck.
I'll try and check in a few hours and see if you've responded to any of these questions. I'm sure lots of others will have good advice for you too.