The doctor read the question, and evaluates his ability to answer your question. This depends on the doctor's specialty and his knowledge about the concerned subject.
We usually opt to answer question that fits to our specialty so that you can get the best evaluation of your condition. So you must wait till a doctor of a specific specialty reads that question.
Furthermore, many of the asked question lack many data and cannot be answered correctly. This is why it is better to develop your question as much as you can.