I have been in some version of this situation. A reconstructive surgery on my hip left my mobility slightly challenged. I walked well enough with a cane but some never damage subjected me to incredible pain if I got jostled. I also am working every day against a pretty bad set of anxiety disorders.
Generally Disney is my happy place and I can manage anxiety there much better than outside the bubble. This particular trip was just before one of my wife's favorite rides closed and we planned to go on it as often as possible, which meant shambling through that line.
Guest Services, generally speaking and for every problem we have ever brought them, has the most amazing CMs. I was very nervous about asking. But I told the CM that was pre-checking the line, "I have a problem I think having a
DAS might help, but it's complicated." and she indicated I should stay in line and talk to a CM with a computer at the desk.
Once up I said simply, "Out of the 2 dozen trips to WDW, this is my first time looking for help here. I've had a severe anxiety disorder that I normally manage very well in the parks, but let run it makes being surrounded very closely by strangers in tight corridors completely impossible for me. Normally I'm okay, and when I'm not I have a battery of Benzedrine tranquilizers to choose from. But this trip, I'm also recovering from a bone reconstruction. It makes me a little wobbly and if I'm jostled too roughly (as will happen in a line) I experience extreme pain. And... And the medicines I take to treat my hip reconstruction make taking my fast-acting anxiety meds impossible."
The CM said "no problem". And I did joke a bit that really if they could just find a way to be sure I got on Peter Pan's Flight 2 or 3 times in next couple days I would be content to just walk the parks and play SotMK and spend money. But in the end, it really wasn't a big deal; 2mg of klonopin helps get the conversation started.
Side note... When doing attractions that load in groups (Haunted Mansion, Jungle Cruise, The Shows, etc...) show a cast member your DAS and ask if you might wait off to the side until the end of the loading and come in last or skip a load cycle and enter first, because loading with an unqueued mob of people will jostle you terribly. Coming in at the back of the pack is an immense help on rides like HM that drop me in a dark crowded hallway then spills me out into a mad rush for the doom buggies.
And always remember, with anxiety, and anything else you receive care for. Discuss your vacation plans with a Doctor. The regimen of activities and medications you are prescribed are meant to treat you during ordinary days. A WDW vacation day will push you both physically and mentally and that can really be a good thing but it might also be a good idea to increase the therapeutic dose of some pain or anxiolytic medications or make fast acting anxiolytics available during your trip.