Rottweiler Drinking lots of..

We have a 11yo rottie lately she has been drinking an excessive amont of water wanting it every single min. of the day She'll like the bowl completly dry. We were worried so we took her to the vet cause she also has a place on her leg looks like a skin tag or something the vet didnt do nay tests acted like there was nothing to worry about,But we are worried along with the drinking of more water she has been peeing in the floor and pooing in the floor,i mean she has had her accidents in the past but its now a every other day thing.Sometimes she gets diahrrea and its like she doesnt know se goint to the bathroom and she'll just be laying there in it.I think we'll have to try another vet. Cause something is wrong here I dont care what the vet says,I looked it up and it said excessive thirst can be caused by-kindney failure,cushings,diabetes etc

Has anyone went throught a similar situation b4 any suggestion would be great we just want to know what s wrong with our doggie

As a pet owner you have the right to request any medical service, even if the vet thinks it is unnecessary. You need to have a complete blood chemistry done. The clinic I work for has in house labs, and you would have results in about 30 minutes. However, other clinics have to send out the sample to another lab. If your vet is not respecting your concern as an owner, go to another one and get a second opinion.