Severe sprain 5 months ago. Twisted ankle bad yesterday. Severe Swelling At back of ankle slight bruise diff walking but can. Can I treat at home.

You can start with. Ice, rest, compression and elevation. If pain persists follow up with doc. .
Get it checked. The "slight bruise" suggests the sprain may be worse that it initially appears. Do see your physician and get it checked. Hope that helps.