T3 recommended by endocrinologist

[Poppygrey]

Hello, I am being treated by an endocrinologist for under active thyroid and keep coming to a halt with treatment when try to increase medication. I was previously on levothyroxine but reacted badly so now on Erfa thyroid but again when try to increase dose I feel awful. Endocrinologist thinks should try t3 only but has said to self source as nhs won’t prescribe and he will monitor. Could somebody please pm me a source to buy from that has safe and easy payment methods. Many thanks