Recently my chest has felt very tight, a mild headache and whenever i yawn i feel light headed. what could be the cause? also very aware of my heart

Many possibilities: Being "aware of my heart" could be normal or abnormal. A 24 hour (holter) recording would distinguish. Chest tightness while resting suggests asthma or bronchitis. Headache has many causes. Respiratory infection could cause both. Dizziness is hard to relate to yawning. I suspect there's another explanation. Knowing your age, past medical history, medications, general health, etc. Would be helpful.

See a cardio: I agree with previous drs. You symptoms suggest some problem with cardiac output. You probably need a full cardiac workup with echocardiogram, etc to work this out.