Shmili, you don’t have to always ask one Rav. It may work out depending on a person and on the Rav.
Sometimes, a person who is already knowledgeable may ask shailos in medicine from a Rabbi who specializes in that, and so on. Of course, the same may be achieved by you asking your Rav and Rav going to a specialist. This is, l’havdil’ like a primary doctor recommending a specialist.