Welcome to HCM
We understand your concerns
You have nothing to worry as you had been to casualty and checked everything including your heart condition, I hope. Normally EKG and Treadmill tests are done to analyse the health of heart alongwith BP and cholesterol test
. If they are OK, then your heart should be fine. Another reason for pain might be due to flu remnant mucous inside the lungs, which need to be extracted. Third type may be stress
after two tough flu bouts. The pain might be psychological one and for treatment you should see psychologist
. Fourth possible cause is acidity and gastritis
. As you had checked everything an found no problem, I suggest, to visit a psyhologist. Get well soon.