How long have you been sitting there? If it has been more than 20 min. you need to stretch.

Try this:
Turn your chair so your legs are in the clear.
Grab one knee and lift it as high as you can for 30 seconds.
Now the next one.

Ok, this is simple...

Reach with your right hand to the chair arm on your left side and turn to look over your left shoulder...a little bit further...good.

Now the next one.

Feel better? Good!