Hello,
According to us you are suffering from hyperthyroidism not Hypothyroidism.
If you are not going to treat hyperthyroidism, insprit of having mass gainer you will not gain weight.
So, my opinion is that if you want to gain weight first treat the cause means
thyroid.
If want to know more or want to contact me, you can contact me directly thru the link below
Next Steps
For more information and to contact me directly visit https://www.facebook.com/pg/doctorplanmydiet/about/
Thanks with regards
Dt.Ankita