Agree with the magnesium. Supplements can help but there are lots of options so check which one with the pharmacist.

As for the clotting - pregnant women are hypercoaguable (meaning extra clotting) to prevent bleeding to death in labour and delivery. It means our blood clots quicker than normal. With a good fluid intake and physical activity you should be able to minimise any risks of developing a blood clot but if you are worried see your doctor. They can arrange an ultrasound to check the leg if needed. You can have residual calf pain after a strong cramping episode.