Hey YEN.
I'm no doctor so I can't advise other than seeing one. That said, I alternate biking, hiking, and running with LOADS of stretching with each. . .sometimes whole walks devoted to stoppin' n' stretchin'. Running and walking do a number on my Achilles but so far I haven't talked to the doc about it. . .next time I'm in I'll bring it up. I earnestly believe it's the alternating and strestcing that keeps it both strong and the problem 'containable'. . .I mean geeez, I hate to run to get medical advice with ever little twitch and grimace knowing full well that there's not a whole lot to be done in my advanced years.