7 minute workout

Lately, I've noticed that whenever I finished performing some excercises especially from those Abs-Workout some portion on my abdominal and stomach area began to ache. I'm scared of having internal injury. Please give some advices.

Unfortunately, I'm one of the beginner

In any kind of exercise, if you notice signs of injury you should stop and consult a Doctor. Or, at least, pause a few days and restart to check if the injury returns/continues.