Hello the impurities in synthetic marijuana as well as other stimulants added to give a more stronger kick to the user are the commonest reason which your heart raced and soreness in the chest occurred .
Per say marijuana itself can cause the above symptoms, so it's a good thing that you have decided to refrain yourself from future use .
As soon as the substance is cleared from your body it should be good . A good sleep , food and avoidance any more stimulants would be good enough .
However if symptoms persists or increase in severity , it's wise you consult a doctor who can physically examine you and check you blood pressure.
Regards Dr Priyank Mody