What Causes Severe Leg Twitching, Weakness In The Hands, Heart Palpitations And Dizziness?

First off: I was diagnosed with cancer back in 2013 but am all good on that now. I have rotationplasty on my right leg and wear a prosthesis and am missing (had to get surgically removed) my lower left lobe in my lungs. I get fairly regular exercise, eat mostly meat and veggies (not much in the way of bread, chips, candy, soda, etc.) (just by taste preference not any diet or anything), am female and 18 years old. I am not currently on any medications, or supplements. I have regular (multiple times a day) twitching/jerking in my right ankle (only). It will, suddenly without warning, twitch/jerk (relatively hard). It seems to be worse when sitting, laying down, etc. or anytime when there s little/no weight on it. My sister has told be that that foot will twitch a lot when I m sleeping (I think it is only in light sleep, not deep sleep). My hands (mostly right) occasionally will start trembling, usually only slightly (not noticeable enough to draw other people s attention) but I can t get them to stop and just have to wait (usually lasts just a few minutes but sometimes as long as 15-30 minutes). The times this has happened is often when I was trying to do something that required really fine motor skills and/or hand steadiness such as writing, taking a photo, etc. I also occasionally experience weakness in my hands; like if I try to hold something heavy or close my hand tightly around something, it hurts through my palms and fingers, and I have a hard time keeping my hand tight on the object (it s like my body automatically tries to open my hand). I will sometimes get really bad hard cramps in my left calf like the whole muscle has tightened really tight and won t let go (really hurts, feels like a knife) (which I assume is just cramping, it usually goes away within 15-30 minutes but is very sore for usually a day or two after). I sometimes (especially if in a stressful/anxiety situation or if physically working really hard) will have my heart suddenly start beating really fast (not just pumping hard but like frantic, sometimes uneven beats), trouble catching my breath, and lightheadedness/dizziness accompanied by a panicky, disoriented, and nauseating feelings. When this happens, I can often hear my heart beating in my ears really loudly, and sometimes the ground starts spinning and I get somehow disoriented as to which way is up. This seems to mostly be triggered if I m physically working hard and out of breath, or when packed in close to a lot of people, or when there are sudden bright flashes of light, but it happens other times and places too, sometimes for no obvious reason (not working hard, calm environment, etc.) I also have sometimes a really weird thing happen where everything seems to get slower and faster, further and nearer, bigger and smaller, etc., etc. all at the same time and it is so scary, disorienting, etc. that it makes me really terrified and panicky. When this happens I can t seem to see anything (I can see things it s just all so jumbled, etc. that I can t make sense of it or figure out where/what anything is) and don t want to/can t seem to move at all; I just curl into a really tight ball and can t seem to bring myself out of it. This will last for anywhere from 5 minutes to hours. When it happens it is usually at night and when I am laying down or laying back (in a chair) and always alone without other people around. I also have trouble sleeping pretty regularly, whole body muscle aches, and sometimes find myself clenching my teeth really hard (even when not sleeping).