Bactrim and rash on hands

I was prescribed augmentin for an infected cut on my ankle. I took it for 5 days before I started getting some seasonal rhinitis pain. Doctor said I had a sinus infection and switched me from augmentin to bactrim, and also prescribed me flonase for the non-allergic rhinitis. I took 2 bactrim before I noticed drug allergy symptoms. I developed a very itchy rash on hands and feet (worst on wrists and back of ankles). The rash appeared on itching, puffed up for a bit and dissipated to pink/red marks (slightly less itchy).
I also noticed welts (skin bumps) in the soft tissue of the web of each hand and on the inside of each foot above the arch. These are slightly tender. I called the a consulting nurse as soon as the rash started and she said to immediately take a benedryl to keep things from getting worse. It helped a little that night. Went to the doctor and was prescibed hydroxyzine which is like benedryl but stronger and helps with itching. Rash lasted almost 3 days, was worst second day, then dissipated. Welts on hands and feet have persisted for the last few days. Having general aches and phantom prickles in hands and feet, must be healing from the rash.

Doctor thinks this was all delayed reaction to augmentin. I think this was immediate reaction to bactrim. Pharmacists seem to think bactrim too.

Whichever caused it, I have stopped both and only continue on the flonase which seems to help with the sinus issues.

I haven't heard of anyone having the same kind of soft tissue welting/swelling between the thumb and forefinger. Has anyone experienced this with a rash caused by allegic reaction to antibiotics?