Scalp eatching amd usage of minoxidil.

I got too much hairfall when I was detected with a tsh level more than 150. I went to a dermatologist to ask whether it's normal and will stop automatically or I need some medication for it. He suggested me tugain 2% soln without even warning me about the side effects and longterm usage. After using for 3months I got severe scaling and some small bumps on my scalp with burning and etching sensation. When I went again for a solution to this issue he gave me a replacement of tugain 5% gel (more cost effective than 2%) and Nizral shampoo. Then only I got to know that I am trapped with the usage of minoxidil and I can't stop it if I want. So can you please suggest if I use this gel for the time being, can I start using the 2% soln, once my scalp problem is solved. Does this Nizral shampoo cause hairfall? Is there any way to stop using minoxidil for lifelong?