My Teenage Daughter is a Mystery - Help

My daughter (17F), 5'4", 148 lbs, biracial (white/Asian) has been suffering from a myriad of complaints since 2021. In 2021 she woke up without any memory. She didn't know us, her dog, her bedroom, her school, etc. She was 14 at the time and her behavior and cognitive skills regressed to about 5-7 years old. After taking her to every ER in town, no one had any clue what was happening. After 2 months, she started behaving normally again (still had big gaps in her long-term memory) and had no recollection of the past 2 months. That's when the physical symptoms started. Debilitating headaches, nausea, muscle weakness, fatigue. She started passing out repeatedly (100s of times) a day, she would lose use of her legs, or sometimes experience total paralysis. One night she looked as if she was have a seizure or a stroke and she was paralyzed. We called 911 and had her transported by ambulance to the ER. In the ER, they said she didn't have a stroke or a seizure. At this point, we'd been to so many specialists and were at a loss, but the ER doctor said, "It's all in her head." We asked him to clarify and he explained that since she suffered from depression and anxiety, he was sure she had "conversion disorder" and could move her legs, etc. We felt like the depression and anxiety stemmed from her health problems, but he thought she was probably depressed and anxious prior and that caused her health problems. We found a specialist for FND and they diagnosed her with FND, depression, and anxiety and prescribed DBT therapy which she has been doing since 2022. She also sees a psychiatrist who prescribes Cymbalta. Her physical symptoms are not getting better, they are getting worse. We believe she has FND and we fully accept that diagnosis, HOWEVER, we also think there is something physical going on as well. She's been seen at a headache clinic and nothing they prescribe helps her. She has pain in her joints now and she's weak. She only passes out 1-3x a week now and lately it's been because of pain rather than anxiety. Two weeks ago she woke up with excruciating pain in her lower right abdomen. We took her to the ER and after 3 separate trips, 2 ultrasounds (one that couldn't see her appendix and one that said her ovaries looked normal), and 1 CT (that said her right ovary looked abnormal), the latest diagnosis is "gas." Yesterday she had another ultrasound on her ovaries and that doctor concluded gas as well. We've seen a total of 5 doctors. Three say, "That's weird. Might be FND causing/creating the pain. Might be something going on. Huh. Bring her back if she feels worse." And two say, "It's gas. Take a walk and work it out." Gas for 2 weeks? Gas that's so painful she passes out? Her stools are normal and regular. She has an appointment with a GI in March (the soonest we could get in). Pain is getting worse. I went through all the results of recent tests vs prior tests and found she's anemic, has an "enlarged" appendix, and slightly elevated glucose levels (her brother was diagnosed with Type 1 Diabetes in December after 6 months of complaining about his own physical ailments, so I'm asking for a fasting blood test to make sure she doesn't have the same). What am I missing? What else can I ask for? At this point, I'm 1,000s of dollars in medical debt because of my kids, why not add more? I just want them to be as healthy as they can be and have a good quality of life. My son is finally starting to get there but my daughter's quality of life is deteriorating.

ETA: This was literally my first post on Reddit and I was a little nervous to post, but I am so glad I did. Thank you to everyone who took the time to stop and give me really good advice. It has been such a wonderful experience. We have an appointment on Tuesday with her pediatrician and now, thanks to all of you, I have a full list of what I'd like done next. Thank you.