won't sleep

Jessica
Hello my 6 month old son just won't sleep. He takes about a two hr nap during the day  and wakes up all the time at night. If I lay him by himself he wakes up within an hr but if he's in our bed he wakes up a few times a night. I have a 21 month old as well and 3 months pregnant so I need my sleep but I'm not getting any due to him not sleeping.