Dear patient
This looks like trivial trauma which has resulted in that patch (called as superficial thrombophlebitis),happens due to crashing of small capillaries
Next Steps
apply hirudal cream on effected area to get rid of this patch
for pain management take a muscle relaxant +NSAID (eg miofree A4, zerodol th4 )etc etc for 3 days
do take antacid empty stomach for 3 days as well
can apply any diclofenac gel for pain relief
Health Tips
icing on the effected area (patch )