Hello I have gone through your question and understand your concern. In my view the rash developed over the exposed area is contact dermatitis due to the inflatable tubing that caused skin irritation. Most of the rubber and inflatable tubes are coated with chemicals and as such latex can cause skin irritation, it is absolutely normal. The right thing done is application of cortisone and aquaphor. The scab will go away in a week without any intervention. Avoid scratching the skin, application of aquaphor twice a day help keeping the area moist till skin recover. Cortisone is not need as redness and irritation is absent. As it is clear the now, avoid exposing skin to latex or rubber. During sports like tubing try to cover your skin as much as possible with clothes and use hypo-allergic gloves when required. Good luck. Hope your concern is answered. Thank you.