Lower Leg Pain

Hi everyone I am new to this forum and am in need of some advice. (Sorry about how long this is)

I first started running a few years ago when I bought my first pair of Asics GT2140 (I need a support shoe) and loved them. Never had a problem. As they wore out I then decided to buy a new pair for the up and coming marathon so I bought a pair of Saucony. Again everything seemed to be going fine, I completed the marathon no problem. A couple of months later I started getting a knee pain and seen a physio who said it was "runners knee" and was told to go back to my Asics so I then bought Asics GT2170 and the knee pain disappeared instantly, happy with that! However recently I have been getting a whole load of lower leg pain. First I got shin splints, once they eventually disappeared, I got very tight calves, now they have gone too I am now getting very tender just above my ankles say on the sides of my legs. It seems I am just getting one thing after another and am wondering now weither the GT2170 were the right way to go? I don't understand how I have been running for years injury free and all of a sudden i'm getting hit with one thing after another.

(Just on a side note, I usually run at a 6 minute mile pace, 3 miles every other day and have done so for years. Usually throw in a long distance run once a week.) 

Again sorry for this very long post any advice would be appreciated!