I have personally found that the most important supplement for dealing with the side effects of chelation is a vitamin C. Are you able to take any vitamin C? If not why not? How about a whole food vitamin C supplement?
I had lots of problems with DMSA until I started taking lots of vitamin C
Another option to consider is DMPS. I had ZERO side effects with DMPS. Plus you only have to take it every eight hours instead of every four hours. Of course you have to have doctors prescription but it's not that hard to get. Also, if you get it be sure to buy it from the Falls pharmacy in Washington state. By far the cheapest source
As somebody else suggested, definitely get the 25 mg DMSA and cut that one and half. That might be all you need
or cut the 25 mg demsa capsule in quarters. That would give you about 6 mg per dosage.