At 15 drops you have a solution with about 1000 PPM available chlorine dioxide and about 200 PPM of that as free chlorine dioxide. Adding the apple juice uses up most of the free chlorine dioxide, but over time the chlorous acid will break down and produce more free chlorine dioxide. You will find that everything is much more stable and predictable if you stick with water and not use apple juice. Since you are not using up the free chlorine dioxide, you will probably have to reduce the concentration of chlorine dioxide by using less drops.
Standard first aid for ingesting chlorine dioxide is to drink quantities of water and not to induce vomiting.
Since you drank it and vomited it back up, your throat has been exposed to chlorine dioxide, chlorous acid, and hydrochloric acid. You most likely have some chemical burning.
Drink plenty of water and try not to cause any further irritation. If problems continue, call a doctor and tell them that you drank bleach and threw it back up. I don't think they understand chlorine dioxide, but they do understand bleach.