The pains of it

Aching shoulder blades need rest.

Workout is a great way to optimise one's body and strengthen it but the onset usually has the body in stages of aches and discomfort that can last for a couple months until such time as the body fully adjusts and sometimes we tend to go a bit overboard with our workouts and distress muscles, in which case it's best to take rest, at least in areas where the aches are happening.
Let the pain completely subside before starting or continuing with workouts.

Cold compressions work best to alleviate pain and in this cold weather it can feel annoying to do it but a few minutes every day in intervals is helpful.
Right, having said that I definitely recommend doing yoga along with exercises, maybe every alternative day and I know that yoga is so off brand but what it does is really help in stretching and galvanising our muscles to keep them from getting hurt with more strenuous workouts .

Sometimes one can experience random muscles spasms and it could drive one to think as to why is it happening especially when you've been working out, but for something like that to not happen one has to be working out for a prolonged period and look towards continuously strengthening your spine, which yoga really helps with.

If the shoulder blades are extremely painful then most definitely avoid anything related to upper body.
If however you still feel guilty about not getting any workout done then perhaps relegate your exercises to only lower body, like variations of lunges and squats which need absolutely no upper body movement, however it's best to take rest and let the area heal completely before moving on.
Another alternative is physiotherapy if the pain absolutely refuses to subside. But give it time and in a few days it will be but all gone after which start with some lower body routine before going to extreme upper body exercises and definitely add yoga routines because it helps in reducing our body's wear and tear.