Period or implantation bleeding. Doc?

Hi doc my fiance has irregular periods due to pcos her last period came on 4 june after taking pinkeva for 21 days after that she stopped taking pinkeva now in this month she hadn't got her period so we did beta hcg test on 6 july and result was 0.46 we did beta hcg test because we came close on 16 Jun it was only rubbing no penetraion again on 6 july we came close it was only rubbing no penetraion she is still virgin.now she started taking meprate from 7 july she took 2 pills per day for 5 days she completed meprate on 11 July and she started bleeding from 19 july till yesterday she used 6-7 pads today morning also she had light spotting but she is feeling weaknesses and some time stomach pain today also doc why is this is implantation bleeding or period please reply doc?