Hello, good question. Shedding of the grafts is very common and normal so don’t worry about that. As far as shampooing, you can wash as you did before your procedure.
At 20 days your transplanted hair is embedded in your scalp now. Any crust or scabbing should have already been washed away. The shedding is normal from your transplanted hairs. Often they shed around 30 days post-op. You can then expect them to lay dormant for a further two months or so before your growth starting. In respect of washing most can return to their normal shampoo regime but if you have concerns regarding your skin condition you should contact your Doctor.