It sounds like Crohn's or IBS. Either of these can cause nausea, constipation, diarrhea, severe abdominal pain, and often effect your ability to properly absorb nutrients which can lead to dizziness, weakness, seizures, heart/blood pressure problems, ect. You should speak to a doctor about it but it may help if you look up a diet plan for people with crohn's/ibs and see if sticking to that helps your symptoms.
https://ghr.nlm.nih.gov/condition/cyclic-vomiting-syndrome
Hey, im no expert or anything, my name is Jessica,just searched your symptoms and found this, worth a read, My mother has similar symptoms but no abdominal pain, she has meniers, but something else that hasnt been diagnosed as well for years. She also has severe vertigo, anxiety, fainting spells and mini seisures after a spell.
This is clearly NOT just anxiety, i have anxiety/panic attacks as well, but they shouldnt be causing you physical pain, doctors are useless now adays!! We basically have to figure it out ourselves, and people think were crazy, but you are not crazy, i feel for you!!! Its frustrating, but be consistant, and change doctors if they arent listening to you, or keep blaming it on anxiety, cause its CLEARLY not anxiety, some of your symptoms are also involved in anxiety, but the others are indicating something is definitly going on physically! When you feel it in your bones that somethings not right, its usually true, you know your body, and its trying to tell you something! Good luck!!
Jess