Little boy in big trouble

My son Máté was born in January 2013 from my girlfriend. The development of the boy cumbersome, a lot of trouble with him. When he was 7 months old he have not moved, due the motion abnormalities he required treatments. When he was 2 years old, psychomotor retardation was diagnosed, and needed additional special therapies. At the age of 3 major motor dysphasia and neurological soft signs was diagnosed, of course special motion therapy and speech therapy progress is still needed. His movement is rough, cumbersome, his communication is poor, usually only gestures and finger-pointing. From this summer (due the lot of treatments) he began to be used recognizable voices and word fragments. Our problem is: since we were not married, there was a need for a statement acknowledging paternity. The mother refused it (to get full legal control over our son), Máté registered with imaginary father, unfortunately, the local laws allow it, and I can't do anything against this thing without the contribution of the mother. From this point the mother exclusively have all parental rights. The mother is completely indifferent to the boy, care and development of completely uninteresting (the mother is under psychiatric treatment due her emotionally unstable personality disorder and bipolar disorder). As the mother did not provide the necessary tasks, I gave up my job to take all father and mother tasks. We lived in a very strong emotional relationship, a perfect symbiosis (Máté never play/paint/eat/bath/laugh with his mother, their emotional relation is poor). This August, the mother moved away with our common son, the issue of paternity has not been settled yet. I could see Máté total of four times since August, the last time on October 8, from this date the mother and/or her partner does not allow it. Since August, the child's development completely stopped, treatment is not running, the examinations were interrupted, his development has been stopped, even regress can be observed (due the broken emotional relationship with me and the missing care/threathments). Between 19, August and 8, October he lost all abilities to use verbal communication, he have decreased activities in movements, he dread from everything and he closing himself into his own world. I not have informations about Máté since 8, October. Since the mother is completely passive on the issue of paternity, to exert full control over the child, the only way to get control and parental rights is the judicial process what is a long and costly process. Meanwhile, the child welfare agency started investigation against the mother because the child is at risk for mothers irresponsible, unhealthy environments and the possibility of any physical/psychological abuse committed by the mother and/or her new partner. The chance that a child protection extract the boy and take care, bigger and bigger every day, unfortunately I'm knocked out from this game, because I have zero rights (only the mother and the imaginary father have the parental rights). The mother does not appear on the court hearings, the procedure is longer and longer without any results. The only option which can speed up the process, judicial DNA test, at a cost 1000-1100 USD, unfortunately, this must be pay in advance (the cost of the whole procedure could reach 1500-2000 USD but all other cost need to paid after the procedure). Earlier, I made a private DNA test (it is much cheaper than the formal proceedings, only 150 USD), but because the mother did not give contribution, it made anonymously, the court did not accept it, of course. When the mother left me alone, I returned to my work, in the last months my financial situation could be stabilized, but the amount of judicial DNA test would need savings of 5-6 months (due to the low local salaries). This time really destructive for the child's emotional and intellectual development, that may extend the catching up (with several years) to the normal children. So I ask for your help for the child, who want come back to his own home soon as possible, continue to develop and do not lose hope completely to the more complete life.