3.5 month old fighting sleep

[Elwyn]

My 3.5 month old DS will breast feed for an hour then play happily with me for an hour. Then he starts to feel tired and he really fights it. He cries and generally the only way we can get him to sleep for a nap is to carry him around in the koala hold against chest (particularly if you walk up and down stairs), shushing him to create white noise effect. He fights it and squirms and kicks and cries but eventually falls asleep for about 30 - 45 min, possibly from exhaustion from all the squirming.
It has got the point where I am finding it difficult to hold him in the only way (Koala Hold) that enables him to fall asleep. My wrist gives out. He is very strong with the kicking and even my 6ft DH has trouble holding him!
Does anyone have any advice for babies that fight sleep, please? I am happy to hold him and people say that holding your baby helps console him but it does not seem to help him that much, it just seems to annoy him (although leaving him in Moses basket is not option since he cries there as well when tired!). We have tried swaddling, white noise, pushing in pram, Amby, Cocoonababy, etc. I love helping him to sleep and feel great sense of achievement when I manage to do it but I feel so frustrated that I am held back by my physical weakness to do so. If I was a big rugby player with large hands that do not go numb at the wrist, it might be easier! Thank you

I was having a similar problem with 3.5 month ds, couldn't get him to settle with a feed. But I think he was overtired I am now putting him down for a nap about an hour and half after he wakes up. He has been much easier to settle and sleeps longer. I think it takes longer settle babies if they are overtired. If this is not the case then you could try a sling.

Would it be a good idea to wind down the pounding up and down stairs? Perhaps move to just walking and shushing, then rocking in rocking chair and shushing, then perhaps rocking in moses basket and shushing. All over a period of weeks/months?
My concern with this is that I know he will initially cry a LOT and for a long time. I suspect it will be basically be days or weeks of crying every nap time and I am dreading it...Plus, he will end up with less sleep at first which is the opposite of what we want to achieve. He may end up completely missing naps because he will cry until it is time to feed or he will end up having fewer feeds and he is already 2nd percentile as it is...