Got this from Heritage perennials website: " Plants may be pruned back at any time if they get too large. Foliage sometimes develops beautiful amber tones in the autumn and winter. Does well in large rock gardens where the plants can be given room to spread. Best with occasional to no foot traffic. Drought tolerant." You probably knew most of that, but the thing about foot traffic caught my eye. Is it being walked on or otherwise disturbed? It is quite shallow rooted, I have some, and it breaks off quite easily if disturbed. If it has recently gotten plenty of rain or water, I'd stop watering it. If it has recently gotten fertilizer, I'd stop fertilizing it. If it hasn't well then I wouldn't fertilize if it looked very stressed, but I might water it if it hasn't gotten water in 2 wks or so. Hope it will survive.
Laurie