Help! What type of disease do I have?

My age is 12+ now. Let me tell you my problems from the begining. Since the last few years, I have been suffering from various diseases, one after the other that has been affecting my attendence in my school and tuitions. But, my teachers refuse to believe me. Earlier I used to have diseases related to the digestive system, like dysentry, diarrhea, indigestion etc. But later on, my health started getting worse. Other types of diseases like influenza, skin diseases etc. also started to affect me. I have suffered from jaundice twice and chicken pox once. And now, I am suffering from something strange. I have been suffering from a throat infection and a regular fever for over a week. The fever is a bit strange. I feel feverish at a particular time of the day i.e.- between 2:45 p.m. to 3:45 p.m. My father gives me a medicine and then, after sometime, I get relief. But, the next day, I again feel catch the fever at the same time. However, about 4 days back (I took my first bath of the week that day), I started catching the same type of fever between 10:45 a.m. to 11:45 a.m instead. The doctor said that I catch the fever due to my throat infection (I feel pain and/or uncomfortable in my throat, along with common cold). But, the medicines and antibiotics of the doctor were not working. So, we changed the doctor, but no use. There's no improvement. Beside these problems, I have some small red spots like measles or rashes on my right arm. First, I had one or two such spots near the upper portion of my wrist. I neglected them. But, they gradually spread to my arm, then to my shoulder and now near my chest. What are these? I had such fever, throat problems, influenza and these type of spots during my half-yearly examination last year, which were solved by a small treatment of the throat. But, this time, nothing seems to be working. I want to get rid of these problems as soon as possible. But, I'm afraid whether I have or going to have any serious disease. I am tensed. What has happened to me and is it serious? I am in an anxiety. How do I get rid of this? Why do I these frequent occurences of diseases and how do I prevent them? As I already said, they're affecting my attendence in my school and tuitions. And the last two days when, in school, when I wap playing, the joints between my legs and feet started aching so much that I could even walk properly. Whose symptoms are these problems?