Hi dh1990,
I've literally just replied tom someone about the same issue, heres what I put::
Have you tried barefoot running? I used to get shin splints (shin pain) all of the time until I started running on a treadmill barefoot (well, with socks). I don't know if it was because my trainers were making me heal strike, or if it is because we are designed to run barefoot, but it sorted the problem out almost straight away. I know barefoot running strengthens your feet, which in turn will help your run.
You also said you're doing speedwork. Are you sprinting a set distance and then stopping yourself as quickly as you can, eg before you hit a railing, fence, trees? It could also be the "slapping" of your feet as you stop yourself.
Hope this helps
Chris