The most embedded experience in my mind of this happening to me, was going to Dunkin Donuts for breakfast years and years ago and having 2 donuts early in the morning. Right after I felt like I was getting the flu...extremely tired and feeling like all my energy to do anything had left me, I just felt like going back to bed and I barely woke up!
I blamed it on the sugar in the donuts...but now I know that although it could have been the sugar as well, I have major allergies/intolerances to eggs, wheat/gluten and milk, and that donut was a "triple threat".
I used to tell people the feeling was like a blanket going over my head but I could still see, or like my brain just left my body and it was hard to think , or it just felt like I could fall down, or like I was getting the flu. Do you, or someone you know, feel really bad at certain times of the day? Keep track of what you eat. Maybe you feel this way after donuts or after a bowl of pasta, or after eating a sandwich....please get an allergy test and don't continue eating foods that make you feel bad/worse.
Food should give you energy not make you feel like taking a nap.
Try this experiment, one day have a large salad with a few ounces of nuts or seeds or cooked beans or salmon or chicken and a dressing of olive oil and vinegar or a raw foods nut dressing,(no croutons or heavy milk based or processed dressings) how do you feel after the meal? Then, the next day, have a bowl of pasta how do you feel after that meal? Choose what makes you feel good, especially if you have Lupus or any other health issues. Eat to live and feel great!