Im have been doing my splits lately & my ankle & achilles hurt did i sprain it?

Hard to say...: Would need to examine. With the splits you typically stretch the adductor muscles in the thighs and not directly the achilles...But if you have a slight injury/pull/strain, you may be compensating and it could be affecting your achilles and your ankle joint.

Possibly: Depending on a full evaluation, a sprain is possible and treatment would be to rest, ice, and more ice to the area. I'd recommend getting evaluated. Best of luck.