hi, im 17 and i have a question about my peroid.

im on my peroid and this morning i woke up to use the bathroom and get ready for school. when i was walking to the bathroom i felt a huge rush from my vagina. when i sat down there was a blood clot about the size of a tennis ball that fell on the floor (not shape just amount)... and my peroid is really heavy. Ive had no pain and the weird this is ive had my peroid 2 weeks before and it was a regular cycle 4 days when i got off i was haveing sex. does the sex have anything to do with it?