Can I abruptly stop using Minoxidil 2% after 2 weeks? It caused massive shedding and headache. Will the shedded hair grow back?

It would be rare to see massive shedding if you only used minoxidil for 2 weeks. If you are concerned you should see a doctor for a proper exam.

Minoxidil causes shedding in many users during the frst 4-6 weeks. It is possible to stop abruptly. Shedding may continue for many months and many people regrow back to the same density.You'll want to see a dermatologist for further evaluation of your original shedding.  Stress can sometimes cause shedding but one should only explore this as possibility when all other causes have been ruled out.

I don't think stopping the minoxidil will harm you in any way.  However, I'm concerned about the amount of "stress related" hair loss you are describing.  You should seek care from a hair transplant specialist right away to find out if there is another reason causing your hair loss.  

Yes, you can stop the minoxidil if you are shedding in the first couple of weeks with no harm. The hair has not yet been addicted to the drug.,