Hello,
Thanks for posting your query,
If I take from your description, then the situation requires reevaluation by a physician. I want to believe that by right
kidney, you mean right flank as we can not be 100% sure that the pain is coming from the kidney but right sided
flank pain could be as a result of
injury to muscle tissues and organs beneath including kidney and
spleen. If you are feeling hardness and pain around that area, then it is most unlikely due to internal organ damage but rather
soft tissue damage (more peripherally). You could have injured the area without noticing during the accident, when was not noticed probably as a result of slow progress. For example, a soft tissue
hematoma or hemorrhage due to damaged blood vessel could be developing gradually and only present as hard painful swelling some weeks later. The hematoma could even complicate to form an
abscess depending if bacteria affected the area. The rashes could fairly not be related to this injury and if related then it might be likely due to the fact that the kidney is actually injured too.
In any case, your situation obviously requires thorough medical evaluation and subsequently treatment.
Hope this helps