baby barely moving today

I've been feeling baby move around since 16 weeks and now I'm 26+4. He usually moves around a lot like all day but the last few days he's been less active and today he's barely been active at all. I've felt him maybe every couple of hours and it's just a few kicks/punches then nothing. I was out shopping all day and didn't feel him much. Once I got home I thought he might start going crazy but nope, barely anything. I've tried drinking a big glass of water and normally he goes crazy after I eat but neither of those worked. Should I be worried? How do you know if you should go into L&D to get checked?