Hi. I am new to using a CPAP machine and I came across this site when googling how to tell if you have a skin allergy to your CPAP mask. I just started using a ResMed Air Fit F20 mask about a month ago. I have noticed that I wake up with strap marks each morning. That is annoying, but not as bad as the other problem I've started noticing. I keep waking up with tiny bumps in the general vicinity of the air mask. I thought they were pimples, but this morning I have a bump on my right cheek that itches like the Dickens and appears to be fluid filled, but not a pimple. I don't think it is a matter of keeping the mask clean as I have been pretty diligent in cleaning it. I do have extremely sensitive skin. What can I do?