HELP- I need sleep

My baby is almost 20 weeks old (4.5 months) and I can’t seem to get him to sleep at all. Not during the day (he takes 20-30 minute naps) and not at night (he’s up every 2-3 hours and he fussy all night during this 2-3 hour “sleep”). I have to constantly get up at night and rock him back to sleep or give him a paci or adjust him. He’s recently started waking up between 3-5am, staying up for an hour and the going back asleep for 2-3 hours. I need help. I can’t function like this anymore. Advice please. I’ve tried everything.