Two "lead" follicles at 13mm

Tigger

I went in for a tv U/S last week and I was told a lead follicle of 13mm seen in right ovary . I go in 3 days later to check growth and told nothing larger than 13mm but now another 13mm follicle so two "13mm" folls and im very confused wondering if this has happened to anybody else.also between the 2 visits lining went from 5.8 to 7mm im not doing meds or stims or anything just naturally ttc. have also not had a period for 2 months