Vimmy, it sounds like some sort of soft-tissue injury. I'd recommend that you go to a physical therapist; they have treatment techniques and exercises to help heal this kind of injury.
In the mean time, the elliptical sounds like a good option. Perhaps stationary bicycle might work, also? Your ankle bends, but it wouldn't have the jarring that you get from trampoline or jumping on the ground. And if you have access to a pool, swimming is also good cardio.
Jump rope might also be too much jarring right now. However, if you use proper technique, which is more of a bouncing movement on the balls of your feet, only going high enough to let the rope pass under your feet, that
might work. Jumping rope is pretty intense cardio, and can take awhile to work up to, but it's a nice option for cardio.
Here's a good video about jumping rope: --->
Intro Jump Rope A speed rope costs only about $5-6, so you could give it a try. If it's too much for your ankle now, you still might be able to do it later, after your ankle is healed.
