1st, I too, have the same PFS that you mentioned but it goes away quickly and i think i will do some of the mentioned excersizes
2nd, i am prone to achilles tendonitis in my left foot, i always get it when running, mine is caused by over pronation and the solution that worked for me was to get some supportive boots. i use asolo PM400's. they are very heavy in comparison to what you have but for me they are worth the weight. i use them for dayhikes as well and since i don't hike without them i have gotten used to the weight. i saw a podiatrist concerning this issue and she recommended orthodics, but i thought i would try the boots first and it worked for me. but, of course, consult your physician first.
just my 2 cents and probably not worth that.