Chest pressure?

doeie04

I am 29 weeks tomorrow and baby has started to move into my ribs sometimes.
The past week i have had a lot of pressure off and on in my chest and it makes my heart feel constricted. [best way i can describe it] It feels like my heart is doing a fluttery thing, but when i feel my pulse, it is normal, maybe a little lighter.

Is it just him moving up? Anyone else get this feeling?

Edit: It seems to be only when i lay down or sit.