Migraine, Antihistamines, Vascular issues; is there a connection?

I’m a 24 years old female dealing with chronic unexplained health issues. I’ve struggled with migraines since I was 11 years old. Familial migraines with stroke-like symptoms (partial vision loss, aphasia, numbness in my limbs and face, Alice in Wonderland syndrome, etc) to be exact. My grandmother has suffered from them all her life and later on developed some pretty serious neurological issues and ended up having a stroke a few years ago. My mother has them also, but not as severe. Luckily this type of migraine only happens to me a couple times a year. I’m between I’ve always had a lot of headaches/milder migraines in between but nothing too life altering. Until a couple years ago. Summer of 2020 I suddenly got so sick. I would get terrible head and neck pain, severe nausea, my balance was off, I felt very week and had a hard time holding my head up, extreme fatigue, I’d feel very hot almost like I was having hot flashes. This went on for a couple weeks. I saw my doctor, had blood test after blood test, autoimmune panels, tested for Mono & Lyme), MRIs, CT Scans, everything. They couldn’t find anything wrong. I’d get up in the morning and be to work at 8am feeling fine, but by 10am-12pm I couldn’t function and would go home and go straight to sleep. I thought I was going to lose my job and genuinely felt like I might die. As a last resort, I took some cold medicine following the advice of my doctor who was hoping that maybe this was just a bad sinus infection of some sort even though I didn’t have a runny nose or congestion. Almost immediately I felt better and would feel somewhat normal until it wore off. When I ran out of that medicine, I had to buy a different brand. It did nothing for me. I went right back to being as sick as I was before. The only ingredient that was missing in the new brand was Doxylamine Succinate, the antihistamine used in Unisom. It’s specifically a first generation H1 blocker that crosses the blood-brain barrier. I figured that had to be what was helping me in the previous medicine and picked up a bottle of straight Doxylamine. It helped. I never felt 100% again, but it was the only thing that enabled me to get out of bed. Fast forward 2 years to now, and I still have to take it at least once a day, sometimes more, to avoid falling back into the horrible unexplained sickness. A couple months ago, I tried to stop taking it for a 48 hours. I ended up with such severe head pain that I couldn’t hold my head up straight. I could barely even stand up, I was so weak and nauseous. I felt like I was overheating. I actually vomited after trying to go about my day and ended up in bed, not feeling right for days after. Other antihistamines that I have tried do not help. I can’t for the life of me figure out what is wrong with me that specifically this drug helps, but I don’t want to keep taking it forever. It’s not safe for long-term use. I’m already having some side effects like weight gain and memory loss for being on it constantly for 2+ years. I’ve talked to multiple doctors and they all think I’m crazy. No one has offered any insight at all. Another thing I’d like to add is that it doesn’t make me feel tired the way that it should. It actually seems to lift the fatigue I feel what I take it it. Things like caffeine, nicotine, stimulant medications, sugar, heat, and hyper focusing on things also induce or worsen that awful sick feeling I’ve been writing about. Depressants like alcohol and muscle relaxers offer short term relief. Could I have some sort of vascular issue causing migraines? Is the Doxylamine possibly helping to relieve some kind of inflammation in my brain? Could depressant medications be helping to calm some over-active part of my brain? I’m looking for any sort of information, insight, or similar experiences. I’m so scared because I seem to be getting worse. I’m having severe head pain and nausea almost every single day. Sometimes my head feels like it’s going to explode. I feel faint and get hot flashes. My arms and upper body will feel very weak. The Doxylamine helps me get through my day, but just barely, and I don’t want to have to keep taking more and more of it. I feel like I’m losing my quality of life and the person I used to be and my doctors don’t seem to care or even take it seriously. Any info from anyone would be so greatly appreciated. I’m on a wait list to get in with a neurologist, but that won’t be for a few months.