How old?
Strausberg sock will stretch.
To lengthen takes time,plus 10 min
You need to remodel and lengthen.
rest, prolotherapy, maybe some other treatments a physical therapist would suggest
I’m 16, I don’t have a strassburg sock I have went back to the stretch against stair steps I’ve just scaled back the workload and it seems to be good although I assume it won’t last in the long run, I will look into seeing a specialist when I have the time, thanks 
Best idea is to go see a physiotherapist. You’ve kind of self-diagnosed here and that’s not a great idea. You DO NOT want this to get worse.
I’ve had both achilles tendonitus AND a snapped achilles so I can talk from experience. You’re better off treating the injury properly and with professional support, in case you end up with it snapped and lying on your back for a couple of months.
In any case, here is an outline of what I was given to do to recover.
I had achilles tendonitus about 3 years ago and saw a physio. The main ‘exercise’ that was advised was the eccentric calf loading. It’s not a ‘raise’, as in a calf raise, when you do this exercise you only do the ‘lowering’ part. So you use your good foot to assist you to go up on your toes, then you lower your weight using the ‘bad foot’. Best to use a step of some kind for this so there is a full range of motion.
There are two variations on this exercise. One is doing it with a straight leg. The other is doing it with the slightly knee bent.
I completely snapped the same achilles tendon last December and am still walking with a stick now, 4 months later. They said there was evidence of tendonitus in it, although I hadn’t felt a thing prior to the snap. I did feel the snap though.
I’m in physio now and now I can walk on it, the exercises are similar to what I was given for the tendonitus. Although now they encourage ‘normal’ calf raises also. And stretching.
The one thing that both physios said is that the best protection against further achilles problems was big calves. That is, build strength in the calves and you’ll build strength in your achilles tendon and other supporting tendons.
But this is NOT medical advice, just my recollections of my experience, I strongly suggest you get your own advice from a physiotherapist.
Good luck.
Check out mobilitywod.com . There are many informative videos on improving ankle mobility / function including using a barbell roll the achilles to “unglue” and improve the quality of soft tissue. ( Can be very painful but effective ). Also some tweaks to basic calf stretches I have found useful.
ive had achilles tendonitis for 4 yrs and it never ceases to hurt… sometimes hurts alot sometimes not to bad…stretching provides little relief but is better than nothing…my job makes it worse but ive no choice. ice helps
One of the points of the Strausberg sock (when worn overnight) is to prevent your sleeping with the foot in plantarflexion. Otherwise, sleeping with it in that shortened position might be undoing a lot of the world you have been trying to do with your stretching. If you are sleeping with your feet in plantarflexion (out of habit) then this might explain why things are worse in the morning.
Don’t forget under your feet. While the achilles inserts into the heel bone other tendons pick up where the achilles leaves off and sometimes people find that stretching out / foam rolling their arches helps give them dorsiflexion. I find a high bounce rubber ball is the right firmness / give for more focused rolling / trigger release around the ankles.
Sometimes deficit in one movement can result in a restriction in the opposing movement. This one is counter-intuitive. E.g., I got to a point with working my femur external rotation where progress seemed to be stuck. Strangely enough… Getting more internal rotation (which I never took to be problematic) resulted in progress on my external rotation. My point being: How is your ankle pronation? Can you kneel on the ground then sit your butt back on your heels Japanese style so your foot angle is entirely open? Improving that might be (counter-intuitively) the thing to get your dorsiflexion better.
Why do you think your achilles is too short?
What if you (shock horror) stopped stretching it and just did your squats (holding a plate out front if need be). Wouldn’t that… Eventually become smooth and comfortable. With whatever ROM you actually need…?