Progesterone only pill

[Phe1]

I currently take the progesterone only pill but over the past few months have had none stop heartburn and can’t work out why. I’ve never suffered with it previously, even during pregnancy. I’m wondering if this could be due to my pill? As I started taking this pill after giving birth due to breastfeeding doctors thought it’d be more suitable. I’ve been taking it for two years but only recently began to suffer from heartburn which is gradually getting worse - could this be a side affect of the pill?