Pyometra sucks, I have had three bitches on my yard with it over the last two years and one I sent to another yard.
I'd like to share my experience, at the same time had I known about this site sooner...maybe could have saved myself some grief...

Bitch #1 over 8yo, never able to get pups tried to breed again in hopes of pups... Pyometra crept up instead of a pregnancy.
I douched this bitch daily with a betadine solution until her discharge wasn't so nasty and gave her injectable Baytril for 30 days! Injectable was what I had at the time and I went so long because she was still discharging until about day 20 or so. I just wanted to be sure all the infection was outta there before I stopped ab's.

Next heat, it was back, I didn't even get a chance to try and breed her. So this time I tried lutalyse with Cephlexin I knew it was hopeless at this point so before the bitch got to bad off, which surprisingly she never either time really became to sick and never went off her food but made the decision to put her down.

Bitch #2 Came to the yard from a friend and was never right, they said no heat cycle that they noticed but the bitch was puffy. Anyhow after a couple weeks pyo reared it's ugly head again. Not knowing much about the bitch I just thought if Cephalexin with kick it out we'll see if she's worth it. Well it did, nothing more than Cephalexin and this bitch is healthy as a horse and recovered like a champ.

Bitch #3 This was a tough one, 6 yo first time I tried to breed her. She looked like she took at about 5 weeks in, but then she all of a sudden didn't look pregnant at all. I suspected something was up and watched her closely expecting to see discharge. It wasn't until about two and a half weeks later I saw some discharge. Pyo again! This can't be happening! After some research I decided to try Metronidazole, I knew it had been used in women for uterine infection so why not a dog? But I'll be damned I couldn't find anything on dogs. I asked a tech friend and they said they had used that stuff for deep bone infections and Giardia. But after explaining the human use they agreed that it was worth a shot. Fellas that was all I used and she just bounced back with little to no discharge after a few days although it didn't completely subside until about 10 days later and I went another 5 on the Met. All Pyometra's were open.

Again had I been here the advise Jack has given as well as others would have saved me some time, but I was so so surprised to see you use the Met in your treatment. I hope I'm done with the stuff, but I have a feeling I'm not.