How can I get my toddler to sleep through the night?

so for the past while… my 20 month old (just a better idea of his age) stopped sleeping through the night. it use to be he would wake & climb in my bed & knock out & now it’s we are up tossing & turning & talking for a couple of hrs. i’m not sure why… anyone have this happen to them? he was given food & milk before bed. snuggled to sleep & moved to his bed. (normal routine) i even bought a calming bed bath tonight to help him. & nothing is helping. i was hoping for a good night sleep… im 16 weeks pregnant & i 1/2 way through my back out at work today. so i was hoping to get good rest in hopes for recovery… joke is on me i guess.