What Causes Pain In Both Leg Joints Along With Fever?

I am a 24 years old boy.I was into martial arts from 8th grade to 11th grade which is around 4 yrs. I was learning an art which needs too much use of legs. Since my 11th grade I am having a pain in my leg joint (where the leg starts), I am not sure if it is a pain in the bone or anything else. Few of my observations are 1) pain increases in winter and is gone in summers. 2)the pain shifts from right leg joint to left leg joint. 3) pain increases at nit between 8 to 4 but in the early morning around 5:00 to 7:00 the pain goes away as though nothing ever happened. The pain however again comes back soon at around morning eight. I have gone to many doctors. I have done 3 kinds of arthritis test. X-ray of spine and hip bone. Bloodtest. All the reports were very normal except that my ESR is 27. All the doctors have told me that they did not find anything unusual. All said that it would go away soon.I was given an antinflamatory tablet called Mobizox.The pain goes away completely when I take that tablet and its as though I get a new life but one tablet keeps me happy for only 24 hrs and then again I start getting the pain. My pain is repeating every winter from the past 6 yrs. All the readers trust me I become almost crippled when I get this pain. I am not able to sleep the whole night and m not able to move my leg at all. The pain is always there but it increases when I keep my steps. One more thing I noted about the pain is that the pain is a very different kind of pain and I feel as though it is hitting my brain. When it pains too much I also get fever. I don t smoke or take drugs. My weight is 62 and height is 5.10 feet. I will be very very happy if some one helps me. Thank you.