Depends on how she's doing. If she seems fine at 7 days and laying is normal then that may be enough. If she's still having issues, or seems off at all, continue to 10. I usually go a couple days beyond seeing anything off, any symptoms at all. If there is infection and you stop too soon...
It does kind of look more like a shell rather than lash material, at least what I'm used to seeing in mine. Fingers crossed that's what it is, and the calcium helps.
If you see more material like that, a clearer picture might be helpful. Usually when you see lash material, they are no longer laying eggs, the infection stops it. It's very hard for me to say from that one picture if it's lash material or soft malformed shell. Sometimes malformed shells can...
The picture is blurry when I try to zoom in , but that may be a malformed, and soft, egg shell. Did you push it around and see what it felt like? Papery, rubbery, etc.? Does she have access to oyster shell all the time, for calcium? I would give a calcium citrate +D (citracal or generic...
Birds metabolize things faster than other animals, so doses per pound are often much higher. Amoxicillin is usually very well tolerated, I would give the higher dose, at 57 mg per pound of body weight, that is what I normally use with no issues.