Please help my dog cries when i pick him up and has trouble walking?

I have a 8 y/o miniture pincher and he seems fine while hes laying down, he smiles and licks me and looks perky but it was so sad when he tried to get up he cant get his back legs up but then he did and just stood there and then he sat down. today i had his leash on with his harness and was pulling him and tht may have hurt him and also he kept running up and down stairs and he seemed fine early in the day, He eats and drinks. I gave him half a dog aspirin to help with the pain. Please help me i cant take him to the vet now becuz its sunday but i will tom. if hes still having trouble. he also went to the bathroom earlier when i walked him. Early he just yelped when i picked him up/ Thank you so much plz help! oh and i gently touched all his legs and spine and for the short time when he stood up his back right thigh seemed to hurt when i touch it. Whta should i do??