Mine started with huge lymph nodes on the back of my head. About a month later I started to get a rash about 20-40 minutes after eating. It would start between my fingers and grow until it covered me.
The only spot I wouldn't get a rash on was the very front of my neck.
Looking at pictures of where lymph nodes and vessels are, there are none in that spot.
Now the rashes I'm getting are from migrating larvae. They are everywhere and if I don't take Benadryl on a regular schedule the 'tracks' swell up and are intensely itchy.
I also intermittently have intense itching on the palms of my hands and the tops of my feet. :(
If you wait until you're having a reaction to take antihistamines, you're too late. The histamines are already released. You'll just stop more from being released. They don't do anything for reactions that are already underway.