Mostly it happens after evening walk or after sweeping..

It occurs few times a day not after every 5 to 10 mins..

Vaginal pain after 8 month is normal light pain with no abdominal cramps and piercing pain is normal because of excessive weight of fluid and baby the muscles are under a lot of pressure but it is very important to understand the pain is happening very sharp and is happening after every 5 to 10 minutes then you will need to see your gynecologist today

Is it normal?

Same here