I have had quite a few experiences with DMSO and I can tell you that the rash is caused by using too strong a DMSO solution. Below waist you can use more than 50% diluted with distilled water. I also dilute mine with pure Aloe Vera gel. Above waist.. Less than 50% and closer to face I use no more than 30 %. You can also use as eye drop.. 3 to 5% diluted in distilled water.
I stepped on a large hot burning coal last year and it literally stuck to bottom of my foot. I used a stick to knock it off my foot and was in excruciating pain. I hopped back to the house and poured the 99% DMSO in bottom of wash basin and stuck my foot in it. After 20 minutes the pain started to subside but I left my foot in for a good 30-45 minutes and pain was gone.. It never blistered at all (that was amazing). The only side effect from the DMSO I noticed was about a week or two after the skin started peeling off my foot. It wasn't painful, but somewhat like getting too much sun and peeling afterwards. I could go on and on but will sum it up by saying I consider it a staple item in my household and never want to be without it. By the way, that rash comes on like sun blisters and totally disappears in a short while. I post this because I hate to see you miss out on the enormous benefits if it.
The only thing you really have to watch is making sure your skin is clean before applying it. Also, don't use if there are strong fumes nearby. I once put DMSO on a bruise just below my elbow. I then put some nail polish on with the lid off polish bottle and my bruised area started to sting intensely. I rushed over to tap and washed the DMSO off immediately. It was a real wake up call. Also need to let it dry before covering with shirt or pants as it can leach material dyes into skin from clothes as well. if you are applying DMSO, don't take medication or vitamins at same time. Put a couple of hours between that and DMSO. There really are only a few red flags to be aware of and otherwise, it is 100% safe..