Should my kid see a doctor for horrible sleep?

mu

I don’t know what the fck is wrong with my 2 year old but he is a HORRIBLE sleeper ever since he could climb out of his crib at age 1. He has nights where he wakes up at 1 am or so and stays up ALL NIGHT long. Sometimes it’s 3am-7am it varies a bit but he’s up for hours and hours and I can’t figure out why. He’s driving me insane and it’s honestly like having a newborn but the newborn stage never ends.

It kills me. He’s ether up crying, or trying to play, or wants food or something idk but he just stays wide awake and I just lay with him in his bed and repeatedly make sure he doesn’t get up and wake up his brother who’s in the same room.

I’m very pregnant and almost due, my only option is to lay with him because it hurts to hold him while standing up. I can’t let him just cry because it will wake up my other kid who has to be up for school.

I have tried melatonin but it doesn’t work. Seems to just help him go to sleep initially but doesn’t keep him asleep. Should he see the doctor? This seems extremely not normal.

I’ve tried feeding him more before bed but he won’t eat anything but snacks, I tried getting more energy out in the day, tried changing his nap to be shorter, longer, diff times of day, cutting out a nap completely, nothing works. There is no pattern. It’s not happening every night but it’s frequently. Even on nights he doesn’t stay up for hours I still have to go in and lay with him until he falls back asleep for a few mins. I’m also up peeing constantly because pregnancy and holy hell I’m stressed. How am I supposed to deal with this AND a new born in a few weeks?