Toddler sleep help!

Ladies I need your help!

I have a 3 year old boy. And he is really killing me with his sleeping! 😴

Let me start by saying he typically goes to sleep between 7:30 and 8:30pm. (He does nap between 12-2 and does the same when he is at preschool.) He has been waking up multiple times a night calling for me or his dad. And he has been waking up around 5:00-6:00am and won’t go back to sleep. He use to be use a good sleeper and I am not sure what to do. I am exhausted. I have started giving him Zarbees melatonin liquid 1ml an hour or so before bed but it isn’t helping much if at all.

I am sure someone has been through this so give me tips please!