I once had sleep apnea and was given the machine- this was 15 years ago and the mask was rather large- not like the ones of today. I used it for around a year with no problems, but then suddenly I stopped snoring as I had lost a lot of weight, so now the machine sits in my garage collecting dust.
Regarding the issue of cycling with enlarged testicles, I used to race bikes too and you should see the doctor but also experiment with raising and lowering the nose of the saddle and see if any one position gives you relief. good luck to you sir