Help! Should I be concerned?

It has been five months since my little one was born, I had an assisted vaginal delivery with ventouse, I was cut and had a reasonable amount of stitches. After birth I bled for a good 5-6 weeks and then had a very heavy period two weeks after that but lately every time me and my partner are intimate it makes me bleed for a good week afterwards. The bleeding is light to medium flow, so I don't know if its a period or just bleeding? It does not hurt when we have sex and everything feels okay, I was told at my six week check all my stitches had healed. It is only the past month that this has started happening, has anyone else experienced this or might know the cause? Thank you x