Spotting (I think?)

At the time my calendar predicted I’d start my period, I did bleed that day, but only that one time for like 15 mins. The nxt day there was nothing, then a week later (yesterday) I started bleeding again, but only for that day. My period has always been irregular since I was 10, (now 18) . I’ve talked to my daughter about my irregular period & it’s normal. I want to go for a checkup but the office is only seeing “emergencies” . Can anyone tell me or help me with what this is?