After 5 months from delivery we started our sex life again.but while having sex I had lot of this normal or do I need to see a gynaecologist.

If you have had a normal delivery then this pain is due to the episiotomy. The stitches make the vaginal area tighter and it feels uncomfortable the first few times. Also since you have had a long break your body needs to get used to it again. Use KY jelly as a lubricant to make things smoother, ask your partner to be gentle and indulge in more foreplay to increase natural lubrication. Additionally think about contraception as well.