From what you wrote I personally would go ahead and admit myself until the meds kicked in. They can monitor you in the hospital and maybe start another med to jump start your recovery.
Most likely they won't keep you too long so you could always return to school with a sick note. People in college take mental health absences all the time (I know I did).
I wouldn't worry about worrying your mom- she would be much more worried if it got out of hand and something bad happened.
Good luck and take care of yourself!