I need help with my 4 months old 😣

Jazmin

He sleeps for a max of 12 and a half hours in 24 hours... I can't get him to sleep more. He usually naps for any where in between 5 - 40 mins during the day. And at night he sleeps from about 8pm - 6 am. He wakes at about 11.30 then 3.00 then 5.00 then sometimes he stays awake or falls back asleep. What can I do to change this to sleeping through the night like he used to do? He used to sleep for a minimum of 7 hours straight 😣 I just don't know what's happened. It's been like this for a month now. Please help 💕