Does anyone have this effect when lying down

I don't know why but my neck feels so bad when I try to lie down in the day or sleep too long at night. It's fine for 10 hours or so lying down at night but if I try lying down in the day I instantly have to sit up again because it's uncomfortable/nonspecific pain in my neck, kind of headache feeling but not much, sinus pressure instantly increases a lot and pressure in my face and head, nose goes blocked, vision changes a bit but not much.

If I do stay lying down then I get PEM, the flu feeling, and all mecfs symptoms get worse for a while (days, or months depending if I keep doing it - these symptoms improve if I don't lie down in day).

This affects me the same way if I sit on the sofa (vs an upright chair), or if I look down at my phone, or looking down in general at something.

Does anyone have this or know what's causing this? I haven't heard of anyone else having this and it's stopping me from resting properly.