Welcome to HealthcareMagic forum.
Well, it seems you had bruising / subcutaneous bleeding which was responsible for the purple discoloration and that has disappeared. I presume the roll of foil was really hard / heavy. Such a fall might result in internal injuries - a soft tissue
inflammation / rarely a fracture
. X-ray of the foot / ankle can be useful to differentiate and identify true nature of injury
I would suggest you to start on over the counter anti-inflammatory such as Motrin
twice a day for a week and plan to get the X-ray done. Rest adequately and if X-ray reveals no significant abnormality you should be back to normal in a week or two.
Hope this helps.
Wish you speedy recovery