problem doing cardio

[DAYS]

I never had to do cardio until now. My body fat is relatively low and always looking shredded @ 140lbs. I just started running on the treadmill last week because I'm gaining a few lbs in school because there is nothing to do around here and i sit around all day. I was wondering if its just me or are there people out there who after running around 10+ minutes on the treadmill and their tibia muscle (shins) start to get sore. I run for 30 minutes (HIIT), 5min warm up @3.5 then switch back & forth from 7.5 to 3.5 after one minute each until reaching 30min. I am flatfooted. Could that be a reason? I just started running 3x/wk (mon/wed/fri) and the soreness relatively heals on my rest days but it comes back on the days that I run. If I continue running with this condition, is it possible that it worsens to a stress fracture or is this considered a normal reaction? Thanks in advance for all the feedback.

P.S. I wear Reebok Classics to the gym (always comfy) maybe It's because I'm not wearing proper running shoes?

[marblehead]

The Shoes could be the root of the problem, the same as the treadmill.

Stretching and Ice are best for shin splints.
If you can try running on grass, that will be alittle easier on your shins