Welcome to HCM
Rapid heart rate
in your case is due to blood loss .
When we lose blood or are anemic our heart has to work extra hard to supply oxygen to the body.
Dizziness is also due to the same cause.
But you have not mentioned the diagnosis made by your doctor.first of all you need to undergo an ultrasound and some blood test
for checking hemoglobin
and thyroid etc.
Then your gynaecologist can start appropriate treatment for regular period.you may also need iron multivitamin
supplements.so kindly visit your doctor.