What Causes Sudden Sharp Pain At The Back Of Head?

Hi, I'm a 26 yr old female- 130 lbs. I had a few seizures from a high fever when I was 4 and 5. I have sinus disease from an absess that punctured my maxillary sinus cavity. For years, on and off, I've been experiencing sudden sharp fiery pain in the back of my head. It's localized, but never in the same spot, but tends to be towards the right of the middle area. It usually lasts 30 sec. or so and gradually lessens until the pain disappears. Today, I experienced this followed by pain in my left sholder and under my clavical where it meets the sholder and heaviness in my entire arm that has lasted for over 2 hours at this point. The pain is coming and going but the weakness is constant. Also, I've had random other symptoms over the years that have only happened once or only a few times. Once, I was driving and my vision started to black out but did not completely disappear- this was followed by lightheadedness. I've experienced pain in my right eye when I move it side to side- sometimes my pinkys get a slight numb feeling- my fingers also randomly become very cold at times. I also sometimes experience weakness in my lower body when I stand up. It feels like my legs cannot support my body. It takes me a while to straigten up. When this happens I feel like a 90 year old. Several yrs ago, for about 5 or 6 months, I experienced spots on my thigh that would feel "weird" compared to the rest of my leg. If I ran my finger over the area- it felt different. After this time frame- I never experienced that again. I guess it would best be described as if there should be a bruise there but there wouldn't be. More recently, on two occassion, I became very lightheaded while taking a shower. I had to hold myself from fainting and get out asap. I sat down and waiting a while for it to pass. That hasn't happened since. I tell myself I should go see a doctor, but then I feel fine for quite a while..... should I be concerned?