Hey and welcome to DV!

It sounds very much like what many call "Sleep Paralysis" and can be quite scary at times. To simplify it's basicly a state you end up in when you fall asleep to prevent your body from thrashing around when you're dreaming. You usually lose consciousness before this happens and therefore you don't feel the paralysis. In some cases you don't lose consciousness and feel the effects of it which includes hallucinations of all sorts. Know that everything you feel in this state is only made up by your mind, your fear of it will also increase the effects.

Pain, extreme anxiety or fear and problems breathing are common but all you have to do is relax and know they're just made up, you're 100% safe. Whenever I try to DEILD and end up in that state I get some serious seizures, since I've had epilepsy as a child this not very pleasant. With some willpower I just remain calm and start to visualize a dream scene and after a while I'm in it.

Relax next time and visualize a dream. Interact with that dream like touching something and try really hard to feel the texture of the thing you're touching. Just ignore the sensations and know they have no power over you and you'll be fine

If you have any more questions, don't hesitate to ask!