Help me understand

My period is due in 2 days. Since yesterday I have not had an appetite. I tried to eat some noodles late last night and could only eat a small amount. This morning I tried to eat apples and caramel and gagged as soon as I opened it. I went to open the fridge to find something to eat and gagged as soon as I smelled food. I have been extremely tired and have been burping. I have been drinking water so I won’t get dehydrated but I don’t know why I cannot eat. Also, my back is extremely sore at the bottom and I have been feeling nauseous since yesterday. All I want to do is lay around and sleep. Has anyone else experienced this? I want to test but I’m trying to wait until I miss my period because I don’t want to see a negative test anymore.