I am 17 years old, I weigh 59.8 kg and am 5ft5. I have cystic fibrosis and am currently on a blood thinning tablet to prevent clots in my portacath. I am sexually active for 3years but have always used condoms. I started my period on the 16th November and have been having very small amounts come out for the last 2 days. A few moments ago I was in the shower experiencing seriously painful stomach cramps then suddenly a large amount the size of an orange of black/red blood came out in what looked like a clot. I washed it away and didn't think much of it but then the same thing happened again and I started feeling faint and nearly sick. The cramping and clots have stopped now.