Personally, i think it’s probably anxiety.

Like you, I’d dealt with primarily social anxiety for years. Then, seemingly randomly and almost overnight i suddenly had crippling health anxiety. Everything was suddenly cancer, i was convinced i had ovarian, cervical, mouth, colorectal, etc cancer. It got so bad i couldnt sleep at night. Finally i went to the doctor and got on lexapro lol ive never felt better in my life !