I Have Been Having Trouble Eating. I’ve Had Random Nausea

I have been having trouble eating. I’ve had random nausea for 2 weeks and I can’t figure out why. When it first started the nausea was extreme and I occasionally had diarrhea. One time i became weak and couldn’t get out of bed without almost passing out. My heart would beat hard and when I would get out of bed my heart would beat so hard that I felt it in my neck and my vision would turn white. That only happened one day but since then it’s been random nausea and it’s really annoying me. I lost a lot of weight because I havnt been eating enough. What is happening with me?