I get pretty bad tendonitis when I hike/climb (I can hear a lovely squeaking noise when i move my feet after a long climb, which i’m told is caused by fluid being squirted at pressure due to tendonitis in my achilles).
I find that diclofenac (ask your doc, or get just get some ibroprofen if you can’t get diclofenac) and a support works pretty well.
These work for me:
LP Ankle Support with zipper
Also, stand on a step before you ride and do as many calf raises as you are comfortable with in order stretch it out. Then repeat the same exercise when you are finished riding.
For me, there’s not really a cure, but I can certainly reduce the discomfort/pain to a level that i’m comfortable with.