Oxygen change when laying down sleep.

This might be a problem with my head music and not my oxygen level. I recently had to increase my O2 to a minimum of 4 lpm to maintain a sat of even as low as 85-88. I did this on my own as I had no upcoming dr appt. Other than not being able to maintain a level of 02 to keep me at minimum sat I am finding that when I lay down to sleep i determine that I am running short of O2 and need to purge some CO2 so I go through the breath in through the nose for a couple of seconds and exhale slowly through pursed lips. I repeat this 5 or 6 times and it will usually work but there are times when it does not and that scares me pretty good. I wind up getting up, checking my O2 on the oximeter again an trying again when I reach at least 84 or 85. Unfortunately this same thing also happens at 2am or 3am when I have to make a bathroom trip. I need to mention that at all times I have the concentrator pumping air to me at 4 lpm. I am hesitant to increase the concentrator output as it has a max of 5 Lpm and that would put it at the max but I need even higher to exercise and i need to definitely need more exercise. I think that medicare would provide a larger concentrator. Anybody have some suggestions for this scary happening. I am thinking that higher O2 output is the answer but if that is what is needed to live there is only one choice. Nice to be able to vent to understanding souls.