Spotting at 15 weeks

Hi, wanted to check if it's common to have spotting at 15 weeks. I've gone for scan and checks and bb is fine and cervical length is good too. But I am spotting quite abit (have to wear pad). Dr has prescribed progesterone 200mg and bed rest for 1 week plus plus. Just wanted to check if this is common at this stage of pregnancy? Thought it only happens during first trimester 😪😔 #advicepls #firsttimemom #pleasehelp