Welcome to HCM,
Your father had Heart attack
which was treated with angioplasty
and stent placement,I am sure he must be taking other drugs also, but his description of pain looks cardiac origin so please get urgent ECG as soon as possible and consult Cardiologist
and he should take sorbitrate
sub lingually in emergency which can be repeated ,if pain is not relieved he must be hospitalized for further management and investigations.
If there is abnormal EKG then he will be required to stabilized first by medication then re perfusion therapy or angiography
may be required to assess his coronary anatomy,to see are there new blocks or stent is working nicely or not.
In case every thing is fine and tests are normal then optimal therapy may be required only.
Please take care