I'm sorry to hear of this with Chuco. The following contains the considerations we need to have:
1) If Chuco has slowly been losing the use of his hind legs and they are now paretic (weak) or paralyzed, degenerative myelopathy (a Lou Gehrig disease-like neuropathy) is most likely in a German shepherd. There is no effective treatment for this myelopathy (spinal cord disorder).
2) If Chuco is too painful to rise due to hip dysplasia both a nonsteroidal antiinflammatory drug (NSAID) such as carprofen or meloxicam and a narcotic analgesic such as tramadol are reasonable to administer to him in an attempt to enable his rising from his prone position. In this case his legs won't be paretic or paralyzed.
3) If Chuco has suffered a slipped disk, the same treatment as in #2 above can be administered. His vet - perhaps a housecall vet because a 90lb Chuco would be difficult to transport - will want to assess Chuco's conscious proprioception (knowing where one's limbs are in space) and nociception (deep pain perception) and then tell you the prognosis for Chuco's return to function. In this case his legs will be paretic or paralyzed.
4) If Chuco has suffered a fibrocartilaginous embolism (FCE) - an interruption in the vascular supply to his spinal cord - his legs will be paretic or paralyzed but his prognosis is better for recovery than if he had suffered a slipped disk. Many of these patients can walk within days. There is no effective treat for FCE.
Whatever the cause, if Chuco can't get up, he'll become a very difficult dog to hospice. The husbandry needed to keep these dogs comfortable is difficult and time consuming. Do your best to have him attended to by a vet who should be able to give you a prognosis for Chuco.
Please respond with further questions or concerns if you wish.