I have this problem because of lung surgery (long story). I take opioids and benzos everyday but I don't drink. Still, it's about the same thing you are doing, which is combining two CNS depressants.
If you can buy an oximeter that would be the best way to see how much oxygen is in your blood. I use mine several times a day to see if I need to use an inhaler or nebulizer. If you are feeling short of breath that is the best way to test it.
The best way to increase oxygen into your system is to take slow, deep breaths through your nose and out your mouth. I can increase my oxygen by several points just by doing that. Whenever I'm struggling I just repeat "In through the nose...." lol because I heard that all day long when I was in the hospital.
If you believe this is serious then definitely go to a doctor or walk in clinic. You don't want to wake up on the floor with a bruise on the back of your head from fainting. Ask me how I know. Shortness of breath is an indicator of something wrong. It might be as simple as Spring allergies or as serious as bronchitis.