If you are looking for something to swish in your mouth as an immediate chelator for amalgams or something, chlorella is usually used for that. Just guessing but seems you could use DMSA, swish with a it of water, spit out after a couple minutes. Chlorella is cheaper that's all and works great for that. I gargle with sometimes it too.

The 250 mgs 3x/day sounds high to me too but I don't know hat your actual problem is. Mercury poisoning? For serious poisoning, my DR chelated me via IV, oral DMSA for home use afterwards only.

eat lots of fiber to keep your bowels moving with that much DMSA going in. drink plenty of clean water.