I have been using Clonazepam .5 mg. The generic by Mylan is no longer available. My doctor prescribed Brand Klonopin. I am experiencing irregular heartbeats & palpitations. Is this a serious side effect? This did not happen with generic Mylan. Can I stop this medication at this dosage without withdrawals? Is there another benzodiazepine I can try to stop withdrawals? I have been using this medication for several years. Thank you for your advice.