In reply to dr_botnik:
I'm going through a similar experience. My Achilles got gradually worse over a period of about 5 years until I stopped running in June 2015 (having not run that much in any case that year). In Jan this year I saw some runners out doing a trail marathon that I myself had done in 2010, 2012, and 2014 (it only runs every other year) and I was spurred into action.
I visited a local sports physio and did the whole heel-drop, back to running thing. I also got fitted with orthotic shoe inserts to correct a bit of over-pronation. I started with 1 minute run + 1 minute walk *5 and gradually got better until I was running for 40 minutes.
Then I had a set-back, and went back to smaller distances, got gradually better again, and was doing Parkrun and occasional 6 mile runs (at ~ 9min/mile pace) all off-road.
However, I'm now more broken than ever, as the point where my Achilles inserts into my heel (The Calcaneaous) is inflamed and exceedingly painful. I think its "retro-calcaneal bursitis", and its a real pain (in all senses of the word).
So no running now for about 5 weeks, and some different leg exercises to try to sort out my legs. In the mean-time I find that Road-biking (in SPD-SL cleats) is fine, but MTB (I generally use flat pedals (DMRs) can be an irritant.
So, its been a real struggle, and I'm currently not very far forward. On the plus side I've ridden a lot more, and I'm actually lighter than I've been for 14 years.
Rob