What Causes Muscle Spasms?

I am a 35 year old female. I am 5 1 and 116 pounds. I have spondylothesis and degenerative disc disease. Recently I have started having muscle spasms at least every week on different parts of my body. The first one was on my lower back where my vertabrae moves forward. The next one was on my right foot right below my toes in the middle of my foot. The next time it was again my right foot and my left between my arch and heel at the same time. Next it was just my left foot. Then it was my shoulder and it was really big, red, and warm to the touch. Now I have one swollen between my neck and the top of my shoulder. It too, is red and warm to the touch. They start off itching and thats what gets me to notice that they are swollen. The muscles on my shoulders have been sore for about the past year and a half but the swelling as just recently started. I also get very weak in my arms with little exerction (for example, just washing my hair sometimes makes me not be able to hardly lift my arms afterwards). One time the tips of my fingers on my right hand turned blue but went away in about an hour or so. The tip of my left middle finger was numb and tingly for about a week but it has stopped for right now. During the summer when it was really hot, I couldnt hardly do anything in the house (I dont have air conditioning) because I would get short of breath just walking across the room and during the hot months I ran a low grade fever and felt like I had the flu (achy and tired). I have fatigue just about constantly and have for several years now. What do you think could be making me feel so bad all of the time?