I was in a similar situation with my DD for the past two weeks - build up of over tiredness (following a virus I think) meaning she was impossible to settle to sleep and only the pram or endless rocking in a dark room worked. And then she'd wake after only a very short time. And she was unhappy most of the time while awake
The last couple of days she has been transformed however.
I think what did the trick was doing whatever it took to get her some catch up sleep - so, hours and hours walking with the pram on thurs and fri last week, even if she woke and cried I walked until she went back to sleep. I also let her sleep on me rather than putting her in her crib whenever I did finally manage to get her to nod off at home (she slept for much longer lying on my chest as she didn't have to self settle iyswim). I managed to make her sleep a decent amount over Thursday/Friday/Saturday that way.
By sunday, after she had caught up on sleep, I found that all the usual advice like "watch for sleepy cues" and "put the baby down when drowsy" suddenly made sense - whereas before she was yawning all the time and was never drowsy! The last couple of days she has gone to sleep easily and taken long naps in her crib, hurrah <touches all wood in sight>. Sleep breeds sleep as they say.
So i'd say, do whatever it takes over the next few days to get your DS to catch up on sleep - easier said than done I know. Perhaps use the pram if he will sleep in that - even if it means hours of pushing it is worth it.
re sleep training, I think I have read that it won't work with an overtired baby, because they are so "wired" from fighting to stay awake, they will just carry on fighting sleep and get more and more wound up rather than learning to fall asleep. So, likely to work better if you can somehow get your DS some catch up sleep first.
As per the title really, 14 week old baby fights naps (fights/cries being held when tired but can't self-settle if put down!) and will only do short naps in the pram, sling or car (after about 20 mins of motion). No longer falls asleep feeding or in my arms. The only thing that works is swaddle, shuh, pat and rock in the dark...but I have to do this through crying which is horrible. Up until the last few weeks, he'd happily drop off in my arms after eating, and usually have about 3 short (20-40 min naps) and one long sleep in the middle of the day (2 hours ish).
At night he sleeps ok from 7ish to 10 or 11ish, has a bottle, back to sleep after about an hour, then goes back to sleep til 1.30ish...and then wakes/stirs every hour until somewhere between 5 and 7 when he decided he's had enough. Often he ends up in bed with me as he sleeps more soundly (but I don't!) I usually feed him if he wakes fully but no longer falls asleep on his bottle. He is swaddled, white noise, in cot in our room. He was quite a good sleeper until Xmas (waking for a feed 3-hourly and falling asleep on the bottle).
I think it's a combination of him becoming more aware of the exciting world around him and a build up of overtired ness.
I need some ideas to help him fall asleep / stay asleep longer! Is it time for some sleep training?