I think you might want to concerntrate on warming up a bit before you actually start lifting and make sure that you
stretch afterwards. I turn on some music videos and do "Leslie" like walking for five or so minutes before I start my routine workout. You get your blood pumping a little bit and your joints moving and lubricated. The after stretch is just as important.
Here is a link to
an explanation of what is happening and
another page dealing with what to do about it.
I am a newbie to weights also. I did 200 or so miles of Leslie and then started working with weights and bands. It is discouraging not to be able to move.We never woke up feeling like this doing straight WATP. But you and I are moving onto the next level and with any amount of change something is going to be a bit harder. This is part of the deal.
Pay attention to your form, and make sure you are doing things correctly.You can hurt yourself by using bad form.
You might want to put a rest day in the middle of the week ( instead of the weekends) or use a lesser band or weight.
I feel for you- but mainly I feel my own glutes and quads screaming.