My baby is now 4 months old and I want to start sleep training but I’m kinda lost !

He sleep with pacifier only and most of time he wants to be hold . I have really bad arms pain so I can’t keep on like this!!

His sleep routine is I give him a shower , feed him , and 80% of the time he sleeps after . And if not I give him his pacifier and walk around with him. I start sleep routine about 8 pm.

During the day he eats , plays , and sleep for an hour or so.

Sooo what’s the best way to make him learns to sooth him self?? If he wakes up he can’t go back to sleep until I hold him and give hims his pacifier:(

Plus he still wakes up every 3 hours to eats . Shouldn’t he be sleeping for more than that by now? He used to have one long stretch 5-6 hours but but any more!