Hi, don't think that you have Hodgkin's Lymphoma, but I also don't think that it's all in your head.
I think that possibly you are suffering from complications caused by the scarlet fever in your childhood. Start your research there, then be sure to also look into rheumatic fever - which is an after effect of the the strep bacteria that causes scarlet fever and involves various inflammatory and auto-immune conditions. It's sort of like having an allergic reaction to an infection. The body then attacks its own organs as if they were the infection - cross reactivity of antibodies. You might have an atypical case of rheumatic fever, which means that you don't necessarily have all the classic symptoms - like joint pain
One example of many that are possible with you: Your shortness of breath could have been from anxiety, or it otherwise could have been from myocarditis when your own immune system was inflaming your heart muscle. If you had myocarditis, it's very important not to undergo vigorous physical activity at the time, and even long after. When young athletes die on the field, the 2nd most common cause is myocarditis. Ask your doctor if he/she will do an EKG.
Abdominal pain is also involved in some people, etc. Many other things like rashes, low grade fevers.
I don't think that you are a hypochondriac, I think that you have physical causes (but not cancer). It's a good thing that you did make your post so long and detailed.
Or it's possible that you had Kawasaki Syndrome, which causes redness and possibly was misdiagnosed as Scarlet Fever. Either way, we're talking about unusual immune system conditions.
Btw, hives are caused by histamine, which is an immune system chemical.
Antacids for stomach pain, like Tagamet and Pepcid, are really antihistamines. Also, histamine is a neurotransmitter, and is involved in anxiety reactions. See the pattern?
Also btw, almost everybody has had the Epstein Barr Virus, but not everybody has a super strong reaction to it. You should ask if any family members have had unusual immune conditions, like lupus or Raynaud's or rheumatoid arthritis, etc. You might have trouble getting a doctor to look into the possibility of an unusually reactive immune system combined with the early episode (Scarlet or Kawasaki) that created all the problems years after.
(Please make a short response if you read this, It becomes discouraging to make long replies to people and not know if the reply was ever even read. Thanks.)
I'd also think about asking the doc for an EKG. In the U.S., there is a movement to have everybody who enrolls in school sports to get a EKG to prevent the rare on-field cases of Sudden Cardiac Death. I think that's going too far, but that shows the extent of the worry.