over small finger and half of ring finger is a sign of either a ulnar nerve ( peripheral nerve
) injury or a C8 nerve root injury
In your senario-
1) If your using a forearm crutches the stop using it as it can cause compression of the nerves.
2) check for neck pain, radiating pain
or tenderness for any spinal abnormalty cause neurlogical symptoms.
3) see if u can feel any rubbery thickened structure behind ur elbow to feel for thickened nerve.
4)if u have wrist pain then it could be a nerve compression at the canal.
I would suggest u to see a neurologist
before ignoring all these and in mean time avoid crutches.