Luckily, my son did not have regression in behavior or any form of regression . He is just congested and can't sleep because his nose is stuffed up. He has been cranky from lack of sleep (and so have I)! I am sure it is from the DMSA. I have read many other posts about congestion from first round of DMSA. I will not do another round until he clears up. I hope that it will not be too long. BTW, I am giving him probiotics, acidophilous, and other form of gut treatments. Vicky