If what they're telling you isn't working then I wouldn't do it.
I was given shampoo and a scalp treatment by my dermatologist for my SD. I didn't like either one, so I don't use them. I found what works for me. Unfortunately it just takes trial and error. It took me YEARS (yes, years) of trial and error before I found what works, then a wrench got thrown in with the eczema and SD diagnoses.
What does work for me is more naturally based products.
Here's my basic routine atm....
1. Shampoo three times a week. Each time I use Malibu C's Scalp Therapy Shampoo. Conditioners vary, but is either Malibu C's Scalp Therapy Shampoo, their deep treatment, or Darcy's Botanicals pumpkin seed conditioner. I use Malibu C's Scalp treatment once a week and use a daily Leave In too, usually Darcy's Botanicals Peach Kernel Nectar or Darcy's Botanicals Sweet Cocoa Bean Curl Smoothing Cream, which is my fave. I don't use any styling products other than that, but I will use oils on my hair or scalp if necessary.
2. Scalp treatment with Darcy's Botanicals Peppermint Scalp Elixir or a hormonal treatment given me by my chiropractor.
3. Air dry most of the way, then dry just a bit, pull my hair up and forget it.
That's it really. I do keep track of my shedding in the shower and in my brushes. It's WAYYYY down, like instead of getting 100 in the shower alone after 2 days I only get 20.
Incidentally, 40-90 shed hairs a day is perfectly normal.
HTH....and hope you get it figured out.
eta the Darcy's Scalp Elixir is made to help with thinning hair and loss and growth. I don't use it consistently like I should but I've seen a difference anyway!