Girlfriend has been bleeding after her period recently

Hi, recently my girlfriend has been bleeding every few weeks after her period the first time her period stopped a few days earlier than normal, it was 4days long not 6-7, then a week and a half later she started to bleed again like itwas her period but then she noticed that it wasnt like normal period blood, the it stopped and we had sex in which the condom after had clumps of blood on, so we assumed she was on her period, then a few days later she went to the loo and tells me afterwards that large clumps of blood came out whilst urinating, in which she just flushed them down the toilet.Then today she phones me up to tell me that she has bled again.We are both quite worried because we are not reli sure as to what it could be, about 3weeks ago she started a new pill to which after about a week all this started. could it be to do with that or could it be to do with us having sex, or could it be even worse and be a miscarriage, we are very worried an upset and we would really appreciate some answers if anybody could offer them. Thank u in advance for ur help, we hope its nothing serious but please do feel free to email me personally if its something that isnot discussable on the web, if so please just comment on here and i shall send u my email address.Thank u.Any help would be very much appreciated ASAP :-)

Thank you