Sprains, from low to high grades, many can still walk on them. You did not mention how long ago the injury happened, makes a difference. You did not talk about using ice, Ibuprofen, elevation, heat, or simple stretches. All of which can play a role depending on injury and such. If you stretched a tendon or something, it is now irritated, inflamed, and sensitive. Every time it is pushed a bit, it will become aggravated, this can be a continuing cycle for a year plus in many cases. You did not tell us about the swelling or even if there is some, bruising, discoloration, ect..
Ice after practice, heat prior to, use an ace or support of some sort, use some sort of anti-inflammatory med. If there is swelling, Ice 15 on, 15 off, pretty much as often as you can and can take it. If a couple of weeks have gone by and there is no improvement, see a doc.