I'm worried about my dog. She has arthritis in her hind legs and now even more so she has trouble standing and balancing. Last night she threw up and while the second amount was coming out she lost her balance and had trouble standing once again. Also last night she had diarrhea for several hours but was able to control it to make it outside. About 5 a.m. she drank a bunch of water, but she has had no appetitie since eating her dinner last night. She seems very weak. When she tries to stand her legs give out and she falls to the floor (but not all the time). Is her weakness due to the sickness from last night or could she be entering a different phase in her old age and rapidly going downhill? She has on occasion peed on the floor while I was on the way to take her out, and she often has to go out to the bathroom at least one time per night. We really wonder if she is suffering and we are prolonging the inevitable.