My dog is really sick please help!?

so i have a 3 year old mastiff/ golden retriever. He is a good boy! but hes verysick since las night. He kept begging me and begging me to go out but there was a animal outside so i couldnt cuz he would of killed it. He ended up pooping in the house. He would onlydo this is he REALLY had to go. He then pooped in the house all night. very STRONG SMELLING diraraha all over and hes seems very tired. He cant seem to hold it it. It is not in the middle of the next day and hasnt pooped in the last couple of hours. Drank some water and ate a peice of bread. He is now sleeping as hes been doing for a long time. Please what do i do!?