Chronic muscle weakness, soreness, tiredness n neck pain

Hi, i experience a set of condition for four years now-neck pain, all limbs’ muscle weakness n easily tired, muscle sore after doing daily activities, cannot stand/walk for long time (3minutes standing then already feel pain). no problem with bladder, n my energy level is ok. It begin after a car accident. I just having whiplash injury n no other injury.i just seek medical attention after a few days because my neck is still hurting, but x-ray show no fracture. I also feel numb, tingling, n kebas but after my MRI didnt show problem, doc discharge me n said everything will become normal after some time. but after that, slowly i begin to notice that it is harder for me to climb stairs, comb my hair, brush my teeth (i need to lower my hand twice or trice while brushing for less than two minutes), i cant do repetitive movement because my limbs will become tired n when i walk long distance i will feel very sore at my muscle n joint as if i did marathon before that(even though i used to walk far regularly). these pain n soreness will heal after few days. during this time, i was referred for physio n was taught to do exercise to strengthen muscle. in the second year, my condition persist, but no more kebas n tingling all the time. it was just it was easier to feel kebas even when i didnt move for short time.Thyroid test n rheumatoid test all normal. but my weaken muscle n pain was still my biggest problem. my muscle often move at their own until now, especially between thumb n forefingers, muscle below the foot, and many other muscles all over the body. some of them stop when i move, but some dont. now, in the forth year, the weakness is increasing, it is harder for me to stand after sitting on floor, n i can even heard my knee grinding. the neck pain persist since the accident until now, sometimes mild, sometimes moderate in scale. when it worse, ill take medicine such as pcm, tramal. i usually use heat first, but it is just temporary. it is hard for me to fall asleep too due to my extremely tired (lenguh) legs. the tiredness is so bad that i cant fall asleep, n usually i use hot oil alot in order to mask the feeling. i defaulted follow-up for two years now because i move to other state. i have went to GP earlier this year n told i feel my limbs are weak, but maybe because i still can walk n full of energy people dont take me seriously. i am seriously afraid of my condition, kindly give consultation.