Blxm says:Hi rassi, your symptoms could be the beginning of shin splints but it might as well be just muscle pain after some good workouts. In both cases take it easy for a while.
Shin splints is a colective noun for a series of injuries. Just Google and you'll get a load of information. In general the best cure is rest and cooling. When you react at the first signs in most cases cure goes fast. By neglecting the signs some nasty injuries may develop like inflamation and nerve problems.
To prevent shin splints:
Wear good shoes (in most cases shin splints appear at runners that pronate).
Do a good warming up and cooldown.
Build distance up slowly.
Don't do too much sprint, hilltraining and jumping.
Vary your training impact (after a heavy training a light training)
And most important: take your rest, don't overdo it. Rest is part of your training. During the workout you break apart, during rest you build up. Stronger and better than before.
If cardio is your main goal you can also try some crosstraining like biking and rowing (or eventually swimming although that will charge your shin muscles as well).