Weak/shaky/Can't stand up for long and sick!

Has anyone ever felt this way? It's been going on for 3-4 days now. It's like I'm not hungry and I do still eat but I make myself. I get nauseous ALOT, but I seem to never throw up. I've been having bad heartburn, and headaches a lot. I had an bad affection like a month ago and I took medicine my midwife gave me. But I still feel so weak and shaky. Please somebody tell me they've felt horrible like this too????!