Having a cold shower for as long as I could tolerate it was suggested to me by my psychiatrist and a long term counsellor. I was told to stay in there for as long as my body could tolerate it. Also holding frozen ice again for as long as you can is another one.
Here are some more suggestions. Hope you can find some-one who will take your insurance.
https://www.healingfromcomplextrauma....com/grounding