Hello
. I am so sorry you are going through this. I know what it's like to have a whole bunch of terrifying symptoms and being desperate for help and answers.
I would definitely suggest you be evaluated by a Neurologist, Cardiologist, as well as have a Sleep Study for your peace of mind. The Neurologist will do testing to rule out seizures. Also a Sleep Study would really help as you are having most of your symptoms when falling asleep. It could be sleep apnea and your body waking you up with an adrenaline rush when you breathing lessens. If that's the case, a simple C-Pap machine worn during sleeping is all you need. The Cardiologist should do a Holter Monitor test where you go home wearing the heart monitor for several days so any abnormality can be caught during the episodes.
If all is clear then it could be your body reacting to the stress of your recent pregnancy, breastfeeding, and your husband's depression. Your vitamin/mineral needs when nursing are high and stress can cause your levels to dip which could be causing some of your symptoms. Are you taking prenatal vitamins?
Seeing Family Practitioners should have yielded referrals to the above mentioned specialists, but many doctors just love slapping the "anxiety" diagnoses on someone with unusual symptoms (especially female patients) and just leave it at that. Blood work is just one piece of the puzzle and hopefully the zinc deficiency is being treated. Did they also check your magnesium, phosphorus and Vit D levels? I would push for that as well. The body tingling could be an electrolyte issue or also due to hyperventilation when stressed.
Referring back to the anxiety, all of this is taking it's toll, so now on top of your symptoms and whatever is causing them you do have anxiety which will exacerbate any situation. I would try to take slow, relaxing breaths and just pray to God to lead you to a Dr. who can help diagnose you whenever you get overwhelmed.
Regarding the Pulse Oximeter, I have and use one too. Sometimes it takes several seconds for the sensor to read accurately and so when the bars go from high to low it's just adjusting and not always accurate to what's going on with your heart or O2 level at that very second. But when you have an adrenaline rush this might explain the bars (pulse) going down, I go this off another website:
"Adrenaline rush: Your heart is contracting quickly, which is increasing your blood flow. Once in a while, your heart will take a breather, because it needs to compensate for all of the fast beats it is being required to make. When it does pause, that's what causes the thump, or palpitation, that you feel when you are missing a beat."
I have a feeling that what is going on with you is not serious and that you'll be ok but that further testing should be done just in case.
From one "Confusednut" to another, I hope this helps. You will be in my prayers.
In Christ,
Irene
Welcome. 
