What is going on with my cycle?!

So my period is very irregular. It starts after 20 to 40 cycle days, but it's usually very easy to tell when it's coming the day before because I get the usual symptoms (cramps, tender breasts, fatigue, emotional mess, etc.). However, last week I started bleeding unexpectedly when having sex with my boyfriend 😖. The surprising thing is that I just had my period exactly 2 weeks before this, period usually doesn't come early, and I didn't have any symptoms. So it was a very light period and only lasted 3 days. Now another week has gone by and I've felt the period symptoms all day today! What could this mean? Has this ever happened to anyone?