Unexplainable health condition. Cause.

I have been feeling this way for close to two years now. My body can't withstand cold, I'm unbalanced I loose composure, my hands shake frequently, feel like something is stretching me from the inside, my veins are showing allover . I get chills in my joints all over my body especially my hands and hip bones. I already ran FBC, urinalysis, widal test, glucose, HIV. All the test came out clean. I feel like I'm dying from the inside. I can't go 2 weeks without​ breaking down. I could all of a sudden go from feeling strong to serious fatigue, headache and dizziness. To mention I still feel this cold even under hot temperature. My eyes are constantly red and I can't gain weight. I'm skinny now compared to my usual 75k stable weight. Before now I use to workout frequently, so I was very healthy and muscular. I eat well, sleep well and try to avoid unhealthy activities. I'm not sexually active. Most times​ I've treated malaria thinking that was the problem, but evidently its not the cause.