Please know that it's not uncommon for people with chronic health problems to have panicky feelings about dying, especially when there are unusual symptoms and you don't feel like you're getting answers. Your feelings are perfectly normal, even though you're certainly not dying. I've been a Registered Nurse for over 30 years and never thought I would be so disgusted with conventional medicine. I now truly understand why patients seek alternative medicine. In answer to your question, the pressure urticaria affects my entire body. I get symptoms from anything causing friction or pressure on my skin such as on my hands from using tools or carrying heavy items, my knees if I kneel too long, and anywhere my clothing is a little tight. It can even affect my butt if I sit on a hard chair too long.When it affects my feet, I think it helps to elevate them if for no other reason than it's hard to walk, but it still usually takes around a day for the symptoms to completely go away. I'm not convinced we have the same thing but they certainly are similar.
It seems like a lot of women's symptoms get worse around the fourth month. Strange, but keep in mind there's a lot of backsliding then going forward. I continue to wish better health for you. Try to stay positive and strong. Every day without the Mirena is a better day than with it.
Keep posting and let us know how you're doing.