Suggest Treatment For Sprained Ankle

Please type your query here. Since this query I sprained my ankle several months ago. I was able to walk on it but it get swelling and getting better then swelling again for no reason. More rest and it feels much better but a little stiff. I popped / cracked yesterday and it feels looser but now i have pain again. Doctors already x-rayed it and said it wasn't broken (about 3 weeks after injury). Do i need an MRI? What could cause this?
I have never had a sprain or a break take this long to recover.
Thanks,
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