32 weeks and 4 days pregnant. I got very bad rib pain about a day ago. I can't even take in a breath. I feel like my ribs don't want to expand!?

See ur ob. I suggest u see ur OB doc.
Possibly serious. Pulmonary embolism, pleurisy, pneumonia, rib fracture, herpes zoster and intercostal nerve/muscle injury can cause your symptoms, as can psychosomatic causes. Talk to your obstetrician asap about this, as some of these causes can be very serious for your health/life!