Welcome to HCM,
As your routine Gynaec examination is normal, nothing to worry.
The blood drop you got might be due to Aspirin
Aspirin has side effect to have bleeding tendency.
It might give bleeding from any part of the body and many a time bleeding from stomach might give big problem.
Now stop taking aspiration for few days and afterwards consult your doctor who prescribed and let him decide for further use of aspirin.
Ok and bye.