I had the same problem when I was training, so I told my Instructor (Mike Smith) who informed me that it was perfectly normal to feel that way and when we flew tomorrow he would cure me !
A while later I asked how he would manage this and he informed me that the next day he would conduct the lessons at 10,000ft and after that 2500ft would feel fine !!!!
The next day and a few hours at 10,000ft in a Hughes 300 certainly did the job, I now regulary fly above 2500ft, and there are lots of safe reasons why this is a good idea, I took some guys to 4500ft on Sunday and Auto'd down they thought it was fantastic !!