Burning during Sleep Paralysis/ WBTB Question

Hi,
I was attempting SP for the first time, i was laying still for around an hour with a timer going off as my safety net. I think i had viberations and a few sounds.. My body was feeling very dead and my Hands were numb? is that normal? also some other parts were also. I was twitching my body parts to get full effect, after a little bit after, my left arm starting burning and became quite painful, so i jumped out of Paralysis and shook my hands and other places that were numb for 30 seconds or so to get feeling back in them.

Also i've been doing Rhythem Napping with WBTB, i have trouble getting back to sleep before my timer beep's at 8mins then 4,8,12,15,20,20,6..mins. I stay awake for an hour, then i tried 40 mins the day after. Should i stay up for only 30 mins or so?
Also with my timer going off, should i make it 15 mins or so for the first beep? so i can get to sleep?
I think i've been worrying about the timer going off to much and that's not letting me go to sleep maybe?