From the description, the possibilities are either trauma, mid-cycle spotting (in which case clots are rare) and hormonal
disturbance. As your cycles are irregular, it cannot be predicted if you are exactly mid-cycle. I would ask you to see a gynecologist for a physical exam followed by a complete hormonal profile as well as a pap smear
and a trans-vaginal sonogram. If local causes and trauma can be excluded, you need to be investigated for a probable miscarriage
(rare) and hormonal disturbances and treated accordingly. Hope this helps.