In regards to the chins bleeding in heat....
I have had chinss for 2 years .. My grade 7 class and I visited a ranch and rescued 2 from the fur trade ...they gave birth during class time

We housed them together for 6 months with no problems or pregnancies as the kids wanted to see them live as a family ( I teach in an inner city school and this seemd very important to them)
I brought them home for the summer- seperated kits and parents- and never took them back to school.
I thought my female was pregnantand put a pink mini blanket in cage for her to play with , tug on , lay on .. whatever...on which I found a stain...watery blood ... first thought her water had broken ... ?????? but with the happenings later on that evening realized she was in heat. The male woke me in the night crying like a baby, barking, chirping, clucking and just in a frenzy chasing the female. I then realized she was indeed in heat...over 2 years and that is the first it was as evident.
Over the next 2 days I found 2 mating plugs... so hoping all goes as smoothly as first time and babies in a few months.
She is otherwiseas healthy friendly, happy and frisky as ever....so could that stain not have been because of heat?