My throat is hurting low down by my vocal cords. it hurts even from the outside to touch. it causes me to cough. could this be from a vitamin i took the other day that got caught in my throat? it feels like a bubble or something down there?

Pills of any kind do not go near your vocal cords. They go down a separate swallow tube. Sometimes a pill will hang up part way down and leave a sore as they scuff up the site. These usually self heal over time. If this is really interfering with your life they can look down your throat with a scope/camera and identify any sore and what if anything needs to be done.