Dear friend, welcome to HCM!
A normal echo rules out serious heart problem as cause of breathlessness.
Was an ECG done?
The symptoms can be due to a new problem like coronary ischaemia (seen on ECG), respiratory (seen on Xraychest) or others like anaemia
Do you get swollen ankles?
Please get detailed evaluation and accordingly labs.
Dio not worry too much. Psychological reasons can also cause this. So, reduce any worries.
Take care and please keep me informed of your progress.
I hope to have answered your query satisfactorily.