Toddler won’t sleep

Guys I’m at my wits end. My son will be 3 in February and he has never been a good sleeper. Last few months it’s been a mess and the last couple weeks have been a damn nightmare. He still naps “occasionally”, but is a disaster to GET to sleep. He literally won’t relax. He will toss around and fidget and look around and just will not relax and go to sleep. He physically resists me rocking him anymore. I just don’t know what to do anymore. I’ve tried everything and I don’t know what to do anymore. Melatonin helps him relax but ever since we tried giving it to him he’s been waking up 2 hours earlier in the morning. I’m at my wits fucking end. GIVE ME ADVICE. I’m losing it.