I can definitely relate with you.
I had a cold, four weeks ago. My tonsils got red, lymph nodes in my neck got a bit bigger, my throat got red and my nose ran. After one look in the mirror, I saw one of my tonsils bigger than the other. First tought I had: Leukemia/Lymphome, I had a panic attack and went to see the doctor immediately. She was not at all concerned and assured me that I did have a viral infection, the difference in my tonsil size is NOT concerning, and both tonsils are red, but relatively normal in size so are the lymph nodes in my neck.
To tell you a bit about myself, I am diagnosed with carcinophobie. And this is not the first scare that I have unfortunately. I have had many trips to the ER or doctor after finding something wrong with my body, only to be later dismissed. I have my first appointment with the psychiatry next week and I hope they will help. But in the mean time I cannot stop worrying. Despite reassurance from my doctor that there is no reason for concern, I still worry. And despite knowing thta I have a phobia and I am exagerating (maybe) that does not make me any less afraid of being sick.