Sorry to hear that your right buttock is still sore after 5 weeks. Contusions sometimes may take 1-2 months to settle down. If the symptoms are not improving at all after so long, You should get it checked.
You may have the railing abit harder than expected, and there may be a hairline fracture in the bone. This can be picked up on X-rays or MRIs. If so, then the recovery time may take abit longer. You may want to consider some anti-inflammatory medication to help bring down the bruising and soreness as well.
Do also consider cutting down your physical activity and you will recover.
Kind regards
Dr Sean Ng