Collections agency calling me?

I had my baby 2.5 years ago and thought I paid all my bills but now 2.5 years later out of the blue, a collections agency started calling me. They called me at a bad time on Wednesday and I told them I couldn’t talk right then and asked if they could call again the next day, they agreed.

They called me again Thursday, Friday, and again today and I literally missed their call each time but before I call them back… I’m curious if this is suspicious or if it’s normal?

It’s just weird to me that they’re calling 2.5 years after my baby was born, I thought I paid all my bills, and it’s a hospital bill.

When will a debt hurt your credit and when will it not hurt it? How can you tell