stop doing barbell curls, unless you got at least 25's on each side of course
you need soft tissue work.
go to a masseuse and ask her (or him) to work on the sides of the elbow, in the ditches (the soft parts behind your elbow, or rather behind your funny bone) , and the arm itself. (elbow, up half way on the arm )
fyi, this should be rather unbearable at times, and possibly the worst massage you'll ever get, but work through it.
im guessing a doctor suggested you have 'tendonitis' and should lay off lifting and take drugs. he might possibly want to get some mri's to check for tendon damage.
the massage might get you sore for a bit, but it should restore itself. supplement with plenty of high quality fish oil and rest it.
if it still sucks after a week, then i guess the doctors gonna get paid.