An inability to say NO inspite of knowing its probably in our best interest to do so, or "people pleasing" may stem from a fear of rejection, avoidance of difficult conversations, or situations, and anxiety about loss of social stature, catastrophisation about consequences, etc. It is commonly encountered in Anxiety, which is what I am able to grasp from your description.
To be able to specify and guide regarding treatment you may need to seek a psychiatrist or a psychologist consultation.
Meanwhile try some grounding, deep breathing, relaxation techniques to calm yourself.
Next Steps
seek an expert opinion as suggested.
Health Tips
54321 technique, Square breathing, JPMR.
Sleep hygiene.
eat regular meals. try to stay active.