help me please? i'm worried :(?

Basically, I alternate my workouts...a day of deep water running for 45 minutes, and a day of walking at 4MPH at a 9% incline on the treadmill for 70 minutes.

On Sunday, I did my treadmill workout pain free. Monday morning, I went water running and was a little tight afterward, but stretched and was fine. I went through the whole day, still a bit tight in my quads and calves, but otherwise, nothing else. At around 3 in the afternoon, I drove to my physical therapist's office for my regular appointment to help me keep my hips loose, because she believes that a lot of the little aches and pains that I get in my legs are from my sciatic nerve being pinched due to my hips being tight, and therefore causing peripheral nerve irritation in my legs, ankles, calves, etc.

Anyway, when I got out of the car at her office, I noticed that there was a very very dull pain in my lower shin, hardly anything really. I think it became more prominent the more I noticed it because I tend to freak out about injuries. It wasn't point tender at all along the tibial bone at that point. I talked to my PT about it and she thought it was just a peripheral nerve being irritated along my shin bone.

I did my treadmill routine this morning, and it started to bother me toward the end a bit, but it DOESN'T hurt constantly. I get a little twinge of pain maybe every 50 steps or so.

It is a little point tender this morning, but that is most likely because I kept rubbing it yesterday and I probably caused a little bruising. I also CAN'T reproduce the pain with the hop test.

Any thoughts here? Is this something that I should be concerned about? I wouldn't think that my walking routine every other day would cause something like this, but am I incorrect? I just want some other opinions because I can't stop freaking out.