If I had to make a choice between the two I would go for the parasite cleanse at this stage.

You mercury problems aren't going to be getting any worse, can't really say that about the other. Plus then you can do another liver cleanse after and unload some more toxins that way.

you can take some DMSA during your parasite cleanse but you probably shouldn't expect to do 'rounds'.

Just take some (25-50 mgs) before bed every or every other night. I would take the DMSA an hour before any parasite cleanse stuff.