Sudden fatigue - 5 years on CPAP

[vpsdub]

Hello

My sleep apnoea was diagnosed in Dec 2016, in 2017 started to use APAP Resmed Airsence 10 Autoset every night. Since mid-March my daytime fatigue and brain fog increased significantly - checked my stats on Oscar, AHI increased from usual 6-8 to 16-20, likely to cause fatigue. Obstractive apnea low, mainly Central and Unclassified apnea. SpO2 saturation at night around 90 with drops to 84. Rapid shallow breathing at night rate 30-40 per minute, sometimes shortness of breath.  
Not sure why this happened - APAP used at least 4 hours every night for the last 5 years, admittedly mask leakage a bit high, but no fatigue until recently.
In the last few days tried to use CPAP 6-7 hours per night, but still daytime issues - difficult to stay awake, even when driving. 30 min nap helps, but only for couple of hours.
Night sleep - usually ok from 11pm till 2am, after that difficult to fall asleep again.
APAP is Airsense 10 Autoset, F20 Full face mask, pressure 14 CPAP for the last 2 years. Since fatigue started tried decrease pressure to 8.4-10, not much help. Any views how to improve sleep and get rid of fatigue?

Leaks - my problems with current F20 FFM (bought new in June) are a) facial hair; and even more important b) I don't like breathing and rebreathing my own hot humid air (feel like I am in the tropical jungle). A bit of mask untightening helps, but causes leaks. The same problem with N20 mask.
CPAP heat is off, use a fan blowing on me. Ice cubes in humidifier help but only for couple of hours. Any advice how to reduce rebreathing effect (feel of hot humid air after exhale).
Tried to use nasal pillows and N30 nasal cradle - this reduces leakage. It's ok for couple of hours, after that internal nostrils get irritated by airflow.
Age 59, male with diabetes, obesity.  Exercise - 7-8 K steps daily

Thanks

[staceyburke]

It looks like positional apnea where you sleep in a position that cuts off your own airway. Also known as chin trucking when your chin drops down to your Sternum cutting off your own airway.

Have you changed to sleeping on your back or sleeping on a different pillow that is higher? Both can be a cause of positional apnea.

If nothing has changed take a look at the link I have in my signature on collars, you may need one to stop chin tucking.

[vpsdub]

It looks like positional apnea where you sleep in a position that cuts off your own airway. Also known as chin trucking when your chin drops down to your Sternum cutting off your own airway.

Have you changed to sleeping on your back or sleeping on a different pillow that is higher?  Both can be a cause of positional apnea.

If nothing has changed take a look at the link I have in my signature on collars, you may need one to stop chin tucking.

Thanks for your reply. No change of position or pillow in a few years. My sleep position is right side, no feel of chin tucking, but still collar might be good idea