I learned of two very good ways to cope with obsessive thoughts of illness and v*. First one is a medication prescribed to me by my psychiatrist. It's called Seroquel, and it's used in treatment of bipolar disorder, depression, OCD, and schizophrenia. It lessens obsessive thoughts and prevents large breakdowns in response to small things, and stabilizes one's mood (it's also an antipsychotic, but I don't take it for that reason).
The second is a breathing exercise recommended to me by my cognitive-behavioral therapist, with whom I just started work. Essentially, you curl your tongue back to the soft part of your palate, and take a deep breath through your nose (if you sing or do yoga or meditation, you should be familiar with this). You hold in this breath for ten seconds and then let it out slowly through your mouth. It completely clears your mind when you're feeling panicky or obsessive.