Dear friend, welcome to HCM.
did you have these when urinating?
if so, they are like micturition-syncope
and passing out on urinating.
since they are 10-15 sec only, I do not think they can be convulsions.
if otherwise, pl. get evaluated to look for other causes like plain anemia
, heart rhythm problems or brain problems.
pl. consult a physician/ neurologist
I hope to have guided you in right direction.
take care and keep me posted on your progress.
good luck !