Why are my muscles hurting?

ya it probably is because u r sore. if u haven't ever done this much exercise, etc. in one week then ur body is probably not used to it. laying down is a good way to make it feel better but if u r going to be doing exercise like this a lot more u need to try to get ur body used to it gradually by making it a little harder every day. u can't just jump right in and expect to be able to do 100%. hope this helps! :)