Fish oil is good but I don't think it should be your end all. There are some other products that can give more apparent results and help chelate heavy metals, which are prime suspects for development & language delays and nervous system disorders.
Consider Lugols iodine supplements, Magnesium Chloride rubbed on skin, and NCD zeolite. All of these can be found to purchase online.
http://zeoliteautismstudy.com/1-dr-p-clips-audio-420.htm
http://www.alkalizeforhealth.net/Liodine2.htm
http://www.whale.to/drugs/antibiotic_q.html
If it were me I might start with 1 -2 teaspoons cod liver oil. I would also buy Carlson's brand or kirkland as those are not suppose to have heavy metals in them.
I know there is some documentaion on the goodness of flax, But I have also read that flax can be estrogenic. Look it up online - I think I remember reading this. If that is the case, it can affect thyroid, and that cascades to other organs.