Hello, thanks for the query to H.C.M.C.
You got injury
as fall on a stair.
There is a sudden pain ( excruciating) when you walk i. clear cut an indication of fracture
some where near ankle joints or in tarsal bones ( bones of sole).
There is bluish coloration and numbness
, these may be due to some injury.
I would like to advice you please get a blood examination for C BC, calcium level, sugar level and of course ESR
( few calling non-specific but if very high indicative of something wrong).
So first of all get an X-rays of injured parts and also the part which have excruciating pain.
If all these things come normal than take a rest.
Good luck for recovery. Dr. HET