Hello and thanks for the query
Trauma causes soft tissue injury or muscular spasm to the area and it getting pain when you use the muscle like in breathing and stretching the limbs. Follow certain steps to reduce your pain:
1. Do hot fermentation of the area.
2. Take analgesic and anti-inflammatory drugs to reduce pain. Apply local anti-inflammatory gel at the site.
3. Take as much rest as you can.
4. Can bear a rib belt to restrict the movements of the muscles.

Hope this will help you. If not than get your X-ray done and check for rib fracture and consult your doctor.
Best Wishes

Hi
Thanks for your query.
The blunt trauma to your chest have injured the chest musclesand in worst case there might be rib fracture too.
Get X Ray of chest done to see if there is any fracture of ribs.
Notice at your breathing movement of chest , is any part moving paradoxically in opposite direction to rest ? there might be chance of flail chest if yes.
The best thing you can do at the moment is go and get a check up by your doctor and follow his advice.
For pain you can take analgesics and apply local analgesic gel.

Don't neglect.

Hope this helps.
Update here how you stay.

Take care.

Disclaimer: The Expert’s advice is provided for general informational purposes only and SHOULD NOT be relied upon as a substitute for sound professional medical advice, as a complete assessment of an individual has not taken place.Please consult your nearest physician before acting on it. The advice is not valid for medico-legal purposes also