...there's a lot of dubious advice out there, and some good stuff.
Achilles go off the boil when you over load the tissue - so to get them better you need to load your Achilles appropriately. That's not to much or too little, but just right....think Goldilocks.
Stretch nothing (just ads to the over load) but allow other tissue to take some extra, part time load to allow your Achilles to heal. Isometrics have been shown to give good pain relief. Eccentric loading is no longer the be all and end all. Concentric has to be modified to allow adequate loading without increasing pain. Heel raise in your shoe is a good idea and as long as it's still relatively acute NSAIDS (if you can) also may help.
......it will take longer than you expect to get better, probably