My child went through something very similar around 12 to 15 months. Some nights he would suddenly cry or scream despite not being hungry, sick, or uncomfortable.
For us, it seemed to be linked to developmental changes and separation anxiety. There were periods when he woke multiple times a night, and then it gradually improved on its own. We found that keeping bedtime routines very consistent helped.
It was definitely exhausting, and I remember wondering if it would ever end. Thankfully it did get better with time. You're definitely not alone in experiencing this.