Suggest Treatment For Shortness Of Breath With Cpap Machine

I recently had to put on a cpap machine at a level of 16. I am noticing that I have a shortness of breath and that my back hurts. I also taste the machine when I cough during the day. I am using distilled water, have washed the machine and hose and am familiar with using cpap machines since my husband has been on one for over 15 plus years. I had a sinus/cold for 3 weeks and was treated for it and then went for the sleep test. I go to the sleep machine people for a check on Friday but am really having a problem breathing and can't get the taste out of my mouth of the air/machine. What would you suggest? They told me that my aphea is very serious since my oxygen level goes down to 50 when I have I stop breathing and my heart goes crazy. Any suggestions?