My 3 week old choked/strangled on vit d drops. if it got into her lungs, what will happen? could it cause something like pneumonia or dry drowning?

Not really: It's unlikely that you will notice any sequelae from this little event. The reason we cough and "choke" - it's our body's way of protecting itself and trying to keep stuff out of the lungs. Even with this protection sometimes, rarely stuff will get by, but most of the time actually nothing ever occurs. The tiny amount of medicine given for infant Vit D drops is inconsequential. Relax. It's okay.

Follow: If you notice any respiratory problems such as coughing a check up is advised. Most likely there will be no problems. Holding the baby at a 30 degree angle helps to avoid choking.