When to call doctor

I’ve been feeling movement pretty regularly the past few weeks and the past few days it’s decreased quite a bit. 24 weeks with an anterior placenta. Today I really haven’t felt baby move at all, I’ve eaten, poked, and I’m currently in the bath to see if that helps at all. I have an appointment on Thursday so I really don’t want to call if I don’t have to, but it’s really stressing me out. If I do call, what should I say?