What's your question? Ask

It sounds like it may be azalea lace bug. This article will help: https://www.gardeningknowhow.com/ornamental/shrubs/azalea/azalea-lace-bug.htm If there are no signs of lace bug, then it could also be azalea gall. This disease commonly occurs in early spring on new leaf growth. The leaves become curled, fleshy, and pale green to white. Affected leaves eventually turn brown and should be removed and destroyed. However, it is most likely attributed to lace bugs, as they generally cause bleaching of the leaves.

Have you noticed any insects on the tree itself? Any insect holes on the trunk/branches or signs of insect damage on the foliage? It will become clearer what to do after looking under that sod. A closer examination, and identification, of these insects should be your first priority. There are a host of insects that could be damaging to your tree, such as the black vine weevil which attacks root systems and may be the cause for the weakened state of your tree. If your insect issue is not addressed, the tree will likely continue its decline.

For more information about pieris japonica, please visit the following link:
https://www.gardeningknowhow.com/ornamental/shrubs/japanese-andromeda/grow-japanese-andromeda.htm

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

Do little to the plant except make sure it is watered well.
Keep the soil moist while it settles into it's new location.
2 to 3 inches of hardwood mulch will help it retain it's moisture.

In the spring you can clean up any dead plant material and fertilize it.
Here is a link to refresh you on the care.
Good luck.

https://www.gardeningknowhow.com/ornamental/shrubs/japanese-andromeda/grow-japanese-andromeda.htm

Yes, you can cut off the flowers after they have faded. You can cut the entire raceme (the portion of the branch where the flowers were) but don't cut off the part with the leaves.

I have not been able to determine a reason for the color change on your plant.
Too much sunlight, cold temperatures even reverting if you shrub is a Hybrid are possibilities.