I just got on the website to ask the exact same thing, I've been having twitches in my left knee mainly since this morning but sometimes also lower in my calf. I'm getting the twitch as I'm typing this! I got a bit worried but now it seems like it's a common thing.. I do get it in my arms but I feel like that's when I overwork on my laptop. I can feel my heartbeat in my throat and my stomach on most days, it's a bit frustrating, do you also get the twitches in your back? Is the knee twitch accompanied by some sort of pain/numbness of the knee or thigh?
I hope and pray you feel better, you can try putting a pillow under your knees when lying down or sleeping at night, I also apply moov or a type of heating cream in hopes that it relaxes the muscle.
Sending you hugs xx

I don't get it in my knee, but I definitely get twitching in my hands/fingers, sometimes in my feet and legs, and I had some twitching in my lower lip previously.

Yes. If I have my foot at a weird angle, I look like the ever ready rabbit, with my leg and foot shaking up and down. I also get twitches where ever that want to pop up.

Same here about the heartbeat sensation

I get twitching all over and just in the past week I’ve had it in my knee for the first time. Not a nice sensation.
Also I get a strong heartbeat feeling all over at various times in the day.