acromio-clavicular injury is very common. External feature is a prominent distal clavicular inflamation.
If the far end of your collar bone is the source of the burn, and especially if the pain stops with application of pressure, it is a common injury, sometimes refered to as "weightlifters shoulder".
You need lots of time for that to heal properly, and in the meantime there is basically no remedial action to continue training without exaggerating the time it takes to heal. first is to tape the clavicle down during times of physical activity. second is to introduce heat therapy to increase blood flow to the injured tendons of the A-C joint. third is to take NSAIDS for pain.
As long as you are training with usual intensity, it will not get better. You can only begin to bear the pain and suffer on with it. The time spent resting and training with extrodinarily low weights is the only way this will actually ever get better. Lots of bodybuilders and weightlifters live their whole careers with this injury, determined to press past it, but all the while it will effect training negatively, and it is always best to heal.