my plants sometimes do that after a long winter & limited watering once every 30 days ...stem tips get wrinkled ...but sometimes a watering will reverse the wrinkles - like it never happened
might add ...another cause of what you are seeing is freeze damage ...but the fix is the same ...remove all dead stuff, and anything that isn't white
as for sun ...full sun ...would help your plant ....my plants get partial sun from about 9am - then full sun from about 11am to around 7pm ...
