Heart palpitations. Way to cure this?

I was prescribed Methylphenidate for ADHD in March. The last time I took it (on March 27th), it triggered a panic disorder (with horrible heart palpitations). I stopped taking the medication. I took anti anxiety medication and an anti depressant for 20 days in May and I felt good on it and my heart palpitations were almost non existent. Now I'm off the medication and I'm mentally ok, but my heart palpitations are back. They're not as bad as before but it's still very uncomfortable and makes me feel really weak. I can't concentrate on my studies due to this. Is there a solution to this problem? I'm feeling extremely hopeless. I started taking magnesium glycinate 2 days ago and I don't see a difference yet. I've also started yoga and meditation 10 days ago. Is there any other natural way to cure this?