Jessica,
My heart breaks for what you are going through. I agree with the others about trying to do as little as you possibly can for now. I had a very similar experience when my oldest son was born. It was not MG related as this was over 20 years ago. I was given a Rubella shot when he was born and had a horrible reaction where my whole body hurt for about 2 months. They diagnosed me with Rhumatoid Arthitis and several other things before they figured out it was the shot. I ran a fever of 105* and I was so weak I would crawl across the floor to get anywhere and one day actually passed out on the floor and woke up there a while later. It was so scary and I felt like I was putting my son at risk. I finally broke down and had a friend keep my son for me during the day when my husband was at work so I could just sleep. We were living in Germany at the time because my ex husband was in the Army. Do you have a friend or family member who could take the baby for 2 or 3 hours a day so you can rest? I know how frustrating it is and I am sure the stress of caring for a newborn is adding to your symptoms. Pregnancy and child birth take alot of out of you and even in a perfectly healthy woman it takes a while for the body to feel like you did before. You may already be doing this but I would try and sleep as much as possible, nap when the baby does and let the rest wait. Make sure you take a multi vitamin everyday and try to eat foods rich in vitamins. If you are nursing that is even draining you more and plenty of food and rest will help you build up what the baby is taking. I will pray for you and just try to take it one day at a time. I probably need to take my own advice on that one LOL!!!
Take care,
kendra