hmm Achilles, I've been hit with the same thing in the last month. One day it just started to twinge running up a very large hill in the peak district(1200ft of climbing in 3 1/2 miles) . I kept going to the top and just ran through it, bad idea. really struggled to get down, I was hopping and landing on the one good leg etc. and then walked 4 miles back to where i was staying. a week off over xmas did the trick and I started running again as normal. only for the same twinging to happen during a XC race two weeks and about 90miles of training later. cue another full week of rest. today I tried running again and the pain has gone. I will keep just running easy for as long as possible just to be sure.
My symptoms sound identical to yours, significant aching, twinges, next day hobbling etc. Id be very dubious about running through mild pain in the Achilles area. Mild pain anywhere else I say go for it, but the Achilles, not a fun injury and can drag on and on if not fully healed. If you've been pain free for a week get out there and do a test run, just easy running and if you get twinges STOP. Do not run up hills for a while if you can help it.
Been researching ways of stopping the injury from reoccuring, and advice appears to be keep the calf muscles stretched and do calf raises to strengthen them, I shall be doing this and hopefully it'll help, might even get a wobble board to keep the ankles as strong as possible. good luck and let us know how you get on.
Edited: 20/01/2013 at 20:25