Frequent palpitations. Help me out.

Hi.excaltly post COVID first wave i noticed palpitations in my chest and i avoided it but it still continuing so last year 2022 March i had a ECG and holter test done. Both showing normal. And echo also normal..i was on beta blocker medication from last 10 months..i started with the 5mg first 3months later 2.5 mg for next 3 months and then after that to till now i am on concor 1.25 i gradually decreased the course. but today i was on the same medicine i had it on the morning..but from this afternoon iam facing too many palpitations.. iam feeling so nervous and so scary..and with in minute i got 3 palpitations iam so frightened now. And I don't know what's happening with in me. Please help me out.