Oh Amy big first babies are tough! (well mine often was anyways) like everyone else has said it doesn't sound 'un-normal'. Do you think he may have been overtired when you gave him that first difficult feed last night? I know that in my experience nb babies especially in the first 2-4wks really can't cope with being awake longer than 5 or 10mins after a good feed and change so if he had already been awake a while maybe just needed to sleep more than keep feeding, even if that's NOT what he thought. If it were me (now probably not with ds1 ) I woulve given him a feed until he stopped, burped and wrapped for a sleep. Then I wouldve started afresh 2-2 1/2hrs later. I honestly wouldn't recommend letting a nb go 4-5hrs between feeds on a regular basis. Yes you need sleep and by all means a slightly longer gap at night is fine if bubbys happy to but its not good for your milk supply, even if you are engorged and have way too much now that can and likely will change very soon. Also its not great for babies (generally) as I touched on before its very easy for baby to just sleep the day away and then realize they are super hungry and just be frustrated and not be able to self settle enough to feed even when that's exactly what they want/need. Try take it easy on yourself I'm sure as much as anyone can be that he's totally fine and normal, its just stressful for everyone at this stage sometimes.
Also have you got some lansinoh for your nipples? If attachment isn't a problem and youre still sore (which is quite normal for now it'll pass) then it truly works wonders on hurting nips!
The only other thing I can think of is that the mw in hospital may be right about the runny poos, if you are really full/engorged it can be really hard for a little baby to latch on properly to feed and even when they do its likely mostly foremilk they will get which for lots of bubs gives painful wind. What I've found works is to express BEFORE feeding- just enough that you're comfortable and soft enough that baby will be able to easily latch on and also have a let down there already. Be a little careful not to pump to long tho or when you feed you'll get a second letdown and create more milk (better than too little but) generally if you're feeding straight away or within about 10mins should be fine.
Hope you're having a better day today and tonight also