Had A Build-up Of Wax In My Right Ear That

Had a build-up of wax in my right ear that needs to be removed before I can have a mold made of my ear for a hearing aid - it was suggested I purchase Debrox to see if this would help - started doing this tonight and experienced the wierdest thing - put drops in my ear - and I started to hear like a hollow chamber sound out of the left ear and then it went again to the right - went into the bathroom - used Q-tips to try and get any wax out and then flushed both ears with warm water - sort of resolved itself after a few minutes but wasn't expecting this type of feedback - is this a natural thing that will happen when using Debrox Thanks