Interaction with a drowned child?

I previously had a job as a lifeguard which I worked for 8yrs before moving on to my current job. The leisure centre at which I worked was quite infamous as a 7yr old boy had drowned there right before I started working for them. The child wasn't mentioned much by staff and, although it was certainly seen as a tragedy, business there continued as normal.

I was overlooking the pool one day, probably about 3yrs after the aforementioned drowning happened, when I suddenly felt the tugging at the back of my shirt, near by my waist. I span round expecting to answer the question or attend to the child who had just caught my attention, but nobody was there. I thought little of this at the time and went straight back to overlooking the pool. About 5min later, the exact same scenario occured again. I turn round - nobody is there. I put this down to my shirt possibly snagging on my whistle, which was in my back pocket at the time. Though I couldn't really figure how this would of happened, it was rational and pretty logical. The way our shifts worked is, every half an hour we would change position so that we would face a different part of the pool, or stand at the top of an enclosed stairwell to monitor people using the slides. At the change over my next position was just that, at the top of thr slide. This was in, what we call in the UK, the six weeks Summer Holiday, so the place was absolutely full of kids, and, as I made my way up the steps to the top of the slide the queue was all the way down to the bottom. I thought very little of the incident that had just occurred beforehand and went about sending the kids down the slides when i got the signal to do so as normal. At some point whilst being up there I felt the unmistakable feeling of a child grab my arm to catch my attention. I could feel every single finger clasp around the top of my wrist whilst the thumb rested at the point where youd check for a pulse. I look down, and, of course - nobody is there... there were kids all around me, but I was totally transfixed on my wrist. I was looking right at the specific place where I could feel the hand, but nothing at all was there - just thin air. As soon as I jolted my arm away, I felt the hand loosen and then it was gone.

I never mentioned this to anyone and, as far as I'm aware, nobody else ever had anything unexplained or unsual happen to them. I myself never did prior to this, or ever again after it. The only person I've ever told is my mom, as she is a total believer in the paranormal. I myself have no idea what to make of it - I have put it down to 'pins and needles' or a spasm in my arm in the past, but I've never experienced anything remotely similar before or after this event. Coupled with the shirt tugging beforehand does make me wonder. Just thought I'd share this after so many years of keeping it to myself anyway. Thanks.