Suddenly I see (stars)

After the major body ache that we have suffered, the six of us from the dance group were picked to do the Poi ball dance. Poi balls are balls wrapped in sheer cloth with lots of trimmings then tied on long strings that will be worn on your middle and index fingers. Poi is a form of juggling with balls on ropes, held in the hands and swung in various circular patterns, comparable to club-twirling.

Honestly, it was my first time to hear about the Poi. So when the choreographer (Alan) said that he will task people to do it, I told myself it would not be me.
During the rehearsal, Alan asked each of us to try juggling the Poi and to my surprise I managed to swing the Poi balls! Next thing I know, I was cut off from the group who will dance to Celine's I Drove all Night . This made me sad because the steps are good cardios and I'm loving the beat. Alan taught us some steps for the Poi dance. I was doing well until I hit the back of my head with the Poi on my left hand as I swung them to my left. I saw black spots and stars! I thought I was gonna pass out.

Good thing I managed to walk to a chair and I sat down.
So, when you hit your head and see "stars," what are you really seeing?

You are seeing activity in the primary visual cortex. When you hit your head in back, the skull slams right into that part of (PJ Skerrett)

Seeing stars is usually due to a lack of blood reaching the brain, and thus a lack of oxygen. Most commonly this happens after standing up quickly or straightening after bending over. You don't see it all the time because the arteries serving the brain reflexively dilate to maintain pressure, but those reflexes may be disturbed by lack of sleep or food, a hangover, or an infection. Physical trauma may also cause the reflex to malfunction, which is why stars float around Sylvester the Cat's head when he gets bonked.(everything)