[pandys]

I think you will find your having an allergic reaction. If the cups have latex it is a common allergy and will get worse every time, your best bet other than not using it is to get some nitrile rubber sheets or use nitrile glove on the cups.
Most EMS and Hospitals no longer carry any latex items because of allergic reactions . EMTs , nurses and doctors have developed allergies from extended contact with Latex.