My rabbit is very friendly and loving and he wouldnt hurt a fly. But suddenly in may/june he became older...?

and slower and he got a really bad eye infection and he cant really walk properly as his feet are old and withered. So we took him to the vets and she gave us a few options. We could either... put him to sleep as he is getting old now nd they think he could be in pain. OR they could give him some medication and it would amke his eye better and the pain would go away. OR we could make him have a BIG operation so his teeth would get better. We decided to choose the medication because we didnt want to just give up on him and we didnt want to put him in a big operation as it may distress him and that just isnt fair. But the other day me and my father discussed maybe we should put him to sleep because he isnt improoving. okayy he was eating and driking but he just didnt look happy! so we chose a date and we went with that plan. then other day, he started getting more livly and he put his paws up on the wire! should i reconsider putting him down or not? remember he is eating and drinking. :)