I sprained my ankle 4 days ago and it is still quite swollen and very bruised. wondering if i should get it checked for a hairline fracture?

It all depends: Jody - it is certainly possible there is a small fracture. Only a clinical exam and xray will tell for sure. But 4 days is a very short time for it to be all better. Bruising lasts 4-6 weeks for some injuries.

Not uncommon: For a bad sprain, but wise to have it checked out nonetheless.

Have it evaluated.: Pain due to trauma may be due to fracture, sprains, arthritis, muscle, nerve or tendon injuries. Have the foot evaluated so that you may get the appropriate care.