The fact that your throat felt like it was closing too (not just trouble breathing), and that the sensation let up after a while (perhaps from the Benadryl) sounds a lot like an allergic or asthmatic reaction.

The hug makes it difficult to catch a breath, but I don't think I've ever heard of it causing the throat to swell shut.

I know that lesions in the upper C-spine (and/or brainstem too, perhaps) can cause breathing difficulties. Again, I don't know if it would literally close off your throat though. If it was more of a choking sensation, I've had that from the MS spinal lesions, and from GERD. Can you try Nexium to rule acid reflux out?

I have another friend with MS who is going through this too. She has lots of allergies to things, but they are currently leaning towards asthma. Have you ever tried a puffer (there's one available for "emergencies").

Cherie