"Catastrophic Thinking" is on the list of 'Problem Thinking' that is the foundation of Behavioral Therapies (CBT, DBT, etc). It is essentially when one takes little information and immediately jumps to the worst case scenario.

ex. My psychiatrist is concerned by the high calcium in my blood and is sending me to a specialist. OMFG! I I must have lithium toxicity. I will require kidney dialysis, hospitalization to go cold turkey from the lithium and surgery to remove a parathyroid. The scar will be 8in long across my neck. I might die. I will have to wear turtle necks or scarves forever.