There is not a good solution in your case currently. If you can find a job to support your child living fee in US, your spouse may go to Mexico for two years (he can visit you shortly during the two year home residence. Another choice is that he may get the Dr. degree to meet the Mexico Government J-1 requirement.
Another possible chance is that your spouse may try J-1 waiver through IGA if your spouse can meets the IGA J-1 waiver requirements. The following websites have some information on IGA J-1 waiver, you and your spouse may take a look to see whether he has or create the possibility to using this pathway. If he has the possibility, he may find a lawyer to help.
http://www.hooyou.com/j-1/j1_iga_waiver.html
http://www.immihelp.com/j1-visa/home-residency-requirement/interested-government-agency-iga-waiver.html