What Causes Swelling And Pain In The Feet After An Injury?

I injured my left foot at the junction of toes and foot about 3 weeks ago. Pain started the next day when walking and then had a very small bruised area. My foot and especially ankle still swell when I am out and about; the pain is very localized at the tarsal/metatarsal area but the ankle swelling after I walk about in daily activities is concerning. All swelling is relieved in the morning after sleep. Pain is now minimal and controlled with ibuprofine, maybe once a day. I believe the initial injury resulted from a suitcase dropping on my foot from a luggage belt but in the heat of the moment of clearing customs and walking what seemed to be a few miles to taxis late at night, I cannot remember .