Hi thanks for contacting HCM... Here you have chest pain , dyspnea and dizziness like symptom on walking .... So cardiac causes seems most likely here although you are young ... Investigate with ...... 1.Blood pressure measurement 2.ECG 3.ECHO 4.If needed chest x ray done ... If your calf swollen and embolism suspected d dimer estimation done for it ..... Here cough , fever etc not present so respi causes seems less likely ... But if cardiac causes not present than they are ruled out by chest x ray, spirometry etc ... Avoid stress as it would aggravate condition... Take care ..... Consult physician for this.....