It seams like a pain is their for longer then an hour, right?
Here lay a strong possibility of blunt abdominal and testicular trauma/injury
based on the description of the event and you have not mentioned any laceration (cuts) on body parts.
- can lead to a collection of blood pooling inside the organ known as "hematoma", it may not be visible by naked eyes but may be hidden deeply ( the shock wave can create an tiny blood vessels to rupture leading a loss on blood internally in the organ but the cover of the organ will mostly enclosed it so it will not come out but will stay their) eventually it will be healed by absorption and macrophages(blood cell) will engulf the hardened dark blood but will take a long time to regress.
Please take an medical attention, and reasons of it are as follows
1) the pain still their.
2) testis are involved and may lead to permanent infertility
3) issues with some systemic injuries not visible (colon
, bladder) may be involved.
4) pelvic bone(hip bone
in very rare case mostly (hair line crack due to impact)
Here is what they will mostly do
1) do the ultrasound
of the abdomen and testis so they can detect any hematoma,
2) may need a pelvic -x-ray to find out any fractures are present and may cause issue later in life
3) And follow up the guidance by the physician, with required pain medication and required antibiotics if needed to prevent issue of infection.
Please get ultrasound at least .
hope it helps.