This morning I took the dog for a two mile walk. He was running about after a while because he didn't seem too keen to start. He had a runny poo while out which is not normal for him. I took him home, fed him then took him to the groomer. When he left the groomer she said he was a bit unsettled and thought he needed a wee. He jumped into the car and conked out and when he got home he conked out again. He has been outside in the garden but not very active. He is allowed to sit on the sofa but he can't jump up. He wants to try but then stops. Not sure if it's the heat or what, any ideas on what could be wrong. He is 6 and is a Cavachon.