Q.adromeda bush
last year my andromeda bush was suffering so I sprayed it with neem oil and I cut it back. This spring it looked to be healthy again, with lots of bright green leaves. But after a week-long business trip, I returned home to find some brown leaves, some drooping leaves with small rectangular white growths on the underside of two leaves. I held some white paper underneath and shook the whole bush but none of the specks moved so I don’t think the problem is spider mites. Nonetheless, the bush is clearly suffering again and I fear it will die, despite its resurgence just a couple weeks ago. Can anyone help? Thank you.

Andromeda likes soil to be on the damp side.
Slightly moist all the time.
Did the plant dry out while you were away?
The wilting and browning leaves may be a sign of needing more water.
White growths on the leaves may be Mealybugs.
I would again treat with Neem Oil.
https://www.gardeningknowhow.com/ornamental/shrubs/japanese-andromeda/grow-japanese-andromeda.htm
https://www.gardeningknowhow.com/plant-problems/pests/insects/mealybugs-control.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm